How to remove data after share between extension and host app in iOS

Question

I have an iOS app, need to handle user share data from third app. To handle this, I cache the data by UserDefaults in extension module:

NSUserDefaults *userDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.app.share"];

// write data
[userDefaults setValue:[((NSURL*) item) absoluteString] forKey:@"shareData"];

//open app
[self openApp];

After that, app is opened and then can read and handle the data:

NSUserDefaults *userDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.app.share"];
//read data
NSString *data = [userDefaults valueForKey:@"shareData"];
NSLog(@"%@", data);

Till now, everything is ok. App host can get the share data from extension correctly.

However, when I need to remove the data after handling:

NSUserDefaults *userDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.app.share"];
//read data
NSString *data = [userDefaults valueForKey:@"shareData"];
NSLog(@"%@", data);

...use the data and then remove it
[userDefaults removeObjectForKey: @"shareData"]

Then strange thing happens as following steps:

• share data from third app.
• if app no running, then after open, data is nil.
• if app is running, then the app switch to get the data correctly.

That is to say, the data is missing during app launching. What's the reason then?

Answer 1

Find a way. Add a timer or delay, when time is out, remove the key in extension module. It works.

NSUserDefaults *userDefaults = [[NSUserDefaults alloc] initWithSuiteName:@"group.app.share"];

//write data
[userDefaults setObject:[((NSURL*) item) absoluteString] forKey:@"shareData"];
                        
[self openApp];

dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
  [userDefaults removeObjectForKey:@"shareData"];
});