如何创建/使用共享应用程序组容器作为包含应用程序及其在ios中的扩展名之间的缓存存储

Question

Data sharing between app and its extension occurs through common AppGroup. I can use shared app group container as persistant data/file storage. How can I create/use shared app group container as cache storage between a containing app and its extension? Is this even possible?

Answer 1

Yes, you are on the right track. This is possible.

In the Capabilities tab of your main app's target and your WatchKit Extension's target, add an app group, eg, with the name group.myWatchDefaults .

Then you can access the defaults like this:

NSUserDefaults *defaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.myWatchDefaults"];

To add data:

[defaults setObject:[NSNumber numberWithBool:true] forKey:@"myBoolVariable"];

To retrieve data:

 bool watchAppOpenedBefore = [[defaults objectForKey:@"myBoolVariable"] boolValue];

Make sure that you use synchronize after changing the defaults:

[defaults synchronize];

Sometimes synchronizing NSUserDefaults between a Watch app and its parent app using App Groups doesn't work when using Xcode's simulators. However, it works on the actual devices (iPhone and Apple Watch). Therefore, this seems to be a bug in the simulator.