App runs fine in iOS 8, but not in iOS 7 - ios

Question

So, in my app, I want to share something using the UIActivityViewController.
To make sure that the sharing activity was successful, I have this code:
UIActivityViewController *controller = [[UIActivityViewController alloc]
initWithActivityItems:#[text, shortURL, image]
applicationActivities:nil];
[controller setCompletionWithItemsHandler:^(NSString *activityType, BOOL completed, NSArray *returnedItems, NSError *activityError) {
if (! completed){
// Here I do some stuff irrelevant to the question
}
}];
Since I have copied (and modified) this code, I don't want to claim that I completely understand what is happening here.
What I do know, and this is my question, is that the code above runs fine on iOS 8 but not on iOS 7, hardware or simulator.
I dearly hope that somebody can explain to me what is going on here.

Answer 1

The completionWithItemsHandler property is not available in iOS 7, as it was introduced in iOS 8.
What you're looking for is the now-deprecated completionHandler property; if your deployment target is below iOS 8, you can just use this, but if you want to be future-proof, you can check whether the new handler is supported and, if not, use the old handler:
if([[UIApplication sharedApplication] respondsToSelector:(#selector(setCompletionWithItemsHandler:))]){
[controller setCompletionWithItemsHandler:^(NSString *activityType, BOOL completed, NSArray *returnedItems, NSError *activityError) {
if(!completed){
// Out of scope of question
}
}];
}else{
[controller setCompletionHandler:^(NSString *activityType, BOOL completed) {
if(!completed){
// Out of scope of question
}
}];
}
}
Also, you may have omitted this for brevity, but it's important that you actually present the view controller after initializing it:
[self presentViewController:controller animated:YES completion:nil];

Answer 2

OK, so this is what I did. Most likely, Kremelur answered it in general terms, but I am too much of a novice to understand that. So, I copied and pasted some stuff, after some cross-googling. I hope this is of any use to someone.
[controller setCompletionHandler:^(NSString *activityType, BOOL completed) {
NSLog(#"completed dialog - activity: %# - finished flag: %d", activityType, completed);
if (! completed){
// Out of scope of question
}
}];
This code seems to run fine in both iOS7 and iOS8.