5. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
Tuesday, September 3, 13
6. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
Tuesday, September 3, 13
7. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
§ This API remains in iOS7, but you may not need to use it (more on this
later)
Tuesday, September 3, 13
8. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
§ This API remains in iOS7, but you may not need to use it (more on this
later)
§ If you do use it, the execution semantics have changed
Tuesday, September 3, 13
9. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
§ This API remains in iOS7, but you may not need to use it (more on this
later)
§ If you do use it, the execution semantics have changed
o
If user locked screen in iOS6, the background task would keep the phone awake
Tuesday, September 3, 13
10. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
§ This API remains in iOS7, but you may not need to use it (more on this
later)
§ If you do use it, the execution semantics have changed
o
o
If user locked screen in iOS6, the background task would keep the phone awake
iOS7 puts the app to sleep; the app will get a time-slice once the phone wakes up
Tuesday, September 3, 13
11. Background Tasks
§ Ever since iOS4, apps could request extra time to execute after being sent
to the background
o
15 minutes of execution time
§ This API remains in iOS7, but you may not need to use it (more on this
later)
§ If you do use it, the execution semantics have changed
o
o
o
If user locked screen in iOS6, the background task would keep the phone awake
iOS7 puts the app to sleep; the app will get a time-slice once the phone wakes up
Execution time not guaranteed to be contiguous
Tuesday, September 3, 13
13. New App Switcher
§ One of the major changes in the OS
Tuesday, September 3, 13
14. New App Switcher
§ One of the major changes in the OS
§ User can swipe up on app snapshot to kill the app
Tuesday, September 3, 13
15. New App Switcher
§ One of the major changes in the OS
§ User can swipe up on app snapshot to kill the app
o
Unlike in iOS6, this also kills background execution
Tuesday, September 3, 13
22. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
Tuesday, September 3, 13
23. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
o
But update happens after the user is already in the app, so the user sees a transition
Tuesday, September 3, 13
24. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
o
But update happens after the user is already in the app, so the user sees a transition
§ Background Fetch enables an app to update its data in the background
Tuesday, September 3, 13
25. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
o
But update happens after the user is already in the app, so the user sees a transition
§ Background Fetch enables an app to update its data in the background
o
If an app is in the background, it will be assigned a time-slice
Tuesday, September 3, 13
26. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
o
But update happens after the user is already in the app, so the user sees a transition
§ Background Fetch enables an app to update its data in the background
o
o
If an app is in the background, it will be assigned a time-slice
If an app isn’t running, it will be started in the background and then assigned a timeslice
Tuesday, September 3, 13
27. Background Fetch
§ When an app opens, typically it shows fresh data
§ When an app is brought to the foreground after being in the background,
generally the first thing most apps do is refresh their data
o
But update happens after the user is already in the app, so the user sees a transition
§ Background Fetch enables an app to update its data in the background
o
o
o
If an app is in the background, it will be assigned a time-slice
If an app isn’t running, it will be started in the background and then assigned a timeslice
When and how often the app is assigned a time-slice is controlled by the OS
Tuesday, September 3, 13
29. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
Tuesday, September 3, 13
30. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
Tuesday, September 3, 13
31. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
Tuesday, September 3, 13
32. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
No repeating interval
Tuesday, September 3, 13
33. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
Tuesday, September 3, 13
34. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
Tuesday, September 3, 13
35. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
performFetchWithCompletionHandler
Tuesday, September 3, 13
36. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
o
performFetchWithCompletionHandler
Do your work: call the completion handler when you are done
Tuesday, September 3, 13
37. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
o
o
performFetchWithCompletionHandler
Do your work: call the completion handler when you are done
After the completion handler is called, if you have new data, it will create a new
snapshot of your app
Tuesday, September 3, 13
38. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
o
o
performFetchWithCompletionHandler
Do your work: call the completion handler when you are done
After the completion handler is called, if you have new data, it will create a new
snapshot of your app
§ Update UI for App Switcher
Tuesday, September 3, 13
39. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
o
o
performFetchWithCompletionHandler
Do your work: call the completion handler when you are done
After the completion handler is called, if you have new data, it will create a new
snapshot of your app
§ Update UI for App Switcher
§ You can test this via debug properties
Tuesday, September 3, 13
40. Background Fetch API
§ Set the UIBackgroundModes value in the Info.plist to “fetch”
o
This can also be set this via the new Capabilities page in Xcode
§ Set the background fetch interval range on your Application object
o
o
No repeating interval
Time-slice assignment is managed by the OS, the range is set by the developer
§ New delegate callback
o
o
o
performFetchWithCompletionHandler
Do your work: call the completion handler when you are done
After the completion handler is called, if you have new data, it will create a new
snapshot of your app
§ Update UI for App Switcher
§ You can test this via debug properties
o
Also on Debug menu
Tuesday, September 3, 13
42. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
Tuesday, September 3, 13
43. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
Tuesday, September 3, 13
44. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
User is notified via alert or popup
Tuesday, September 3, 13
45. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Tuesday, September 3, 13
46. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
Tuesday, September 3, 13
47. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
Tuesday, September 3, 13
48. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
o
content-available : 1
Tuesday, September 3, 13
49. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
o
o
content-available : 1
When set, the app gets executed before the user gets the notification
Tuesday, September 3, 13
50. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
o
o
o
content-available : 1
When set, the app gets executed before the user gets the notification
Hopefully you can get that new data before the user clicks the alert to bring the app
to the foreground
Tuesday, September 3, 13
51. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
o
o
o
content-available : 1
When set, the app gets executed before the user gets the notification
Hopefully you can get that new data before the user clicks the alert to bring the app
to the foreground
§ Send content-available:1 without an alert in the payload of the
notification
Tuesday, September 3, 13
52. Remote Notifications
§ Since iOS4, notifications could be sent through Apple’s Push Notification
Service (APNS)
§ Often sent to notify user of new data
o
o
o
User is notified via alert or popup
If the user clicked on UI, the app was either brought to foreground or started
Race condition: what if app can’t show new data yet because new data can’t even
start to be retrieved until app is in the foreground
§ iOS7 enables you to send a notification with a new flag
o
o
o
content-available : 1
When set, the app gets executed before the user gets the notification
Hopefully you can get that new data before the user clicks the alert to bring the app
to the foreground
§ Send content-available:1 without an alert in the payload of the
notification
o
This becomes a silent notification and is delivered to the app in the background
Tuesday, September 3, 13
54. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
Tuesday, September 3, 13
55. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
o
Or use new Capabilities UI in Xcode
Tuesday, September 3, 13
56. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
o
Or use new Capabilities UI in Xcode
§ Make sure to set content-available: 1 in the payload
Tuesday, September 3, 13
57. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
o
Or use new Capabilities UI in Xcode
§ Make sure to set content-available: 1 in the payload
§ The application:didReceiveRemoteNotification:fetchCompletionHandler
is called with a non-null completion handler
Tuesday, September 3, 13
58. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
o
Or use new Capabilities UI in Xcode
§ Make sure to set content-available: 1 in the payload
§ The application:didReceiveRemoteNotification:fetchCompletionHandler
is called with a non-null completion handler
o
Call the completion handler when you are done
Tuesday, September 3, 13
59. Remote Notifications API
§ Set UIBackgroundModes to remote-notification in Info.plist
o
Or use new Capabilities UI in Xcode
§ Make sure to set content-available: 1 in the payload
§ The application:didReceiveRemoteNotification:fetchCompletionHandler
is called with a non-null completion handler
o
o
Call the completion handler when you are done
Silent notifications will be rate-limited. APNS does the work to make sure that device
isn’t overloaded – delayed but not rejected
Tuesday, September 3, 13
61. Networking in the Background
§ Before iOS7, you might want to download or upload a resource after the
your app has gone to the background
Tuesday, September 3, 13
62. Networking in the Background
§ Before iOS7, you might want to download or upload a resource after the
your app has gone to the background
§ Background Task API would give you a set time-slice
Tuesday, September 3, 13
63. Networking in the Background
§ Before iOS7, you might want to download or upload a resource after the
your app has gone to the background
§ Background Task API would give you a set time-slice
o
What if your operation took longer than the time allowed (i.e. a large resource like a
video or image)?
Tuesday, September 3, 13
66. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
Tuesday, September 3, 13
67. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
Tuesday, September 3, 13
68. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
Works even if your app is in the background or even if it is terminated
Tuesday, September 3, 13
69. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
Tuesday, September 3, 13
70. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
§ BTS manages battery life and data
Tuesday, September 3, 13
71. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
§ BTS manages battery life and data
o
Requests are classified as discretionary or non-discretionary
Tuesday, September 3, 13
72. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
§ BTS manages battery life and data
o
o
Requests are classified as discretionary or non-discretionary
Discretionary requests will only happen when on WI-FI
Tuesday, September 3, 13
73. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
§ BTS manages battery life and data
o
o
o
Requests are classified as discretionary or non-discretionary
Discretionary requests will only happen when on WI-FI
Requests from the background are automatically discretionary
Tuesday, September 3, 13
74. Background Transfer Service (BTS)
§ iOS7 introduces the BTS
§ You can offload network work to the BTS
§ BTS will ensure that the work gets completed
o
o
Works even if your app is in the background or even if it is terminated
If your app wakes up due to background fetch or notification, this is a great API to pair
with it
§ BTS manages battery life and data
o
o
o
o
Requests are classified as discretionary or non-discretionary
Discretionary requests will only happen when on WI-FI
Requests from the background are automatically discretionary
Requests from the foreground can request to be discretionary
Tuesday, September 3, 13
77. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
Tuesday, September 3, 13
78. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
o
API is similar to NSURLConnection
Tuesday, September 3, 13
79. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
o
API is similar to NSURLConnection
§ Adds more functionality than NSURLConnection
Tuesday, September 3, 13
80. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
o
API is similar to NSURLConnection
§ Adds more functionality than NSURLConnection
o
Instance storage of credentials, cookies, and other state (vs. NSURLConnection’s global
shared state).
Tuesday, September 3, 13
81. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
o
API is similar to NSURLConnection
§ Adds more functionality than NSURLConnection
o
Instance storage of credentials, cookies, and other state (vs. NSURLConnection’s global
shared state).
§ If your app goes to the background or even is terminated after you make
a NSURLSession request, BTS service will still complete the request
Tuesday, September 3, 13
82. NSURLSession
§ New object in iOS7
§ Subsumes the functionality of NSURLConnection
o
API is similar to NSURLConnection
§ Adds more functionality than NSURLConnection
o
Instance storage of credentials, cookies, and other state (vs. NSURLConnection’s global
shared state).
§ If your app goes to the background or even is terminated after you make
a NSURLSession request, BTS service will still complete the request
o
Your app is started or woken up when request is finished and you have a chance to
process
Tuesday, September 3, 13
84. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
Tuesday, September 3, 13
85. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Tuesday, September 3, 13
86. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
Tuesday, September 3, 13
87. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
Tuesday, September 3, 13
88. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
NSURLSessionDelegate for high-level events
Tuesday, September 3, 13
89. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
Tuesday, September 3, 13
90. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
Tuesday, September 3, 13
91. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
o
[resume] method to start task
Tuesday, September 3, 13
92. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
o
o
[resume] method to start task
[cancel],[suspend],[resume] control methods
Tuesday, September 3, 13
93. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
o
o
o
[resume] method to start task
[cancel],[suspend],[resume] control methods
Multiple sub-classes for different functions
Tuesday, September 3, 13
94. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
o
o
o
[resume] method to start task
[cancel],[suspend],[resume] control methods
Multiple sub-classes for different functions
§ NSURLSession also has block-based convenience methods as well
Tuesday, September 3, 13
95. NSURLSession API
§ To create an NSURLSession, you need an NSURLSessionConfiguration
object
o
o
Configuration object determines foreground/background execution, whether the
request will use only wi-fi, etc.
Background configuration gets an identifier (string) to use later to retrieve from BTS
§ Implement to appropriate protocols
o
o
NSURLSessionDelegate for high-level events
NSURLSessionTaskDelegate for data-level events
§ NSURLSessionTask really replaces NSURLConnection
o
o
o
[resume] method to start task
[cancel],[suspend],[resume] control methods
Multiple sub-classes for different functions
§ NSURLSession also has block-based convenience methods as well
o
Still need to call [resume] on task to kick off connection
Tuesday, September 3, 13
98. Background Considerations
§ Limited time
o
You still only get a limited time to execute in the background (less than 1 minute)
Tuesday, September 3, 13
99. Background Considerations
§ Limited time
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Tuesday, September 3, 13
100. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
Tuesday, September 3, 13
101. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
§ User control
Tuesday, September 3, 13
102. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
§ User control
o
User can turn off or limit background fetch
Tuesday, September 3, 13
103. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
§ User control
o
User can turn off or limit background fetch
§ Data Protection
Tuesday, September 3, 13
104. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
§ User control
o
User can turn off or limit background fetch
§ Data Protection
o
If you use the recommended levels of data protection, you won’t be able to access
files, keychain, or sqlite DBs when running in the background
Tuesday, September 3, 13
105. Background Considerations
§ Limited time
o
o
o
You still only get a limited time to execute in the background (less than 1 minute)
Make sure to call the completion handlers ALWAYS in less than 1 minute
Use BTS to enhance the work you can do when called in the background
§ User control
o
User can turn off or limit background fetch
§ Data Protection
o
o
If you use the recommended levels of data protection, you won’t be able to access
files, keychain, or sqlite DBs when running in the background
If you need credentials in the background, to lower risk, consider a token that expires
in a short amount of time
Tuesday, September 3, 13
107. Summary
§ The new background execution features help your app seem to the user
to be running all the time
Tuesday, September 3, 13
108. Summary
§ The new background execution features help your app seem to the user
to be running all the time
§ The new NSURLSession and BTS make foreground networking code
simpler and background networking code possible
Tuesday, September 3, 13
