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I am deprecating iOS 9 on a project. One of the differences in the framework is that the openURL method has changed.

iOS 9

- (BOOL)openURL:(NSURL *)url;

iOS 10

- (void)openURL:(NSURL *)url options:(NSDictionary<NSString *,id> *)options completionHandler:(void (^)(BOOL success))completion;

Notice how the method changed from being synchronous to asynchronous.

Since I have a bunch of usages for the synchronous method, I want to create a synchronous wrapper around the asynchronous openURL:options:completion: method and I'm going to update the usages to call this asynchronous wrapper instead.

My first attempt looks like this:

- (BOOL)sync_openURL: (nullable NSURL *)url {
    __block BOOL result = nil;
    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
    [self openURL:url options:@{} completionHandler:^(BOOL success) {
        result = success;
        dispatch_semaphore_signal(semaphore);
    }];
    while (dispatch_semaphore_wait(semaphore, DISPATCH_TIME_NOW)) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:0]];
    }
    return result;
}

Is this a good replacement ? Can it be improved in anyway ?

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  • 1
    \$\begingroup\$ Why don't you want to make your code asynchronous? \$\endgroup\$ – Roman Podymov Feb 20 '18 at 13:08
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That code should work, but blocking the main thread is never a good idea. That's why the method was changed in the first place.

I suggest a deeper refactor of your code so that you use the new async method with completion handler as intended.

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You don't need to do anything special here. Just change to the new method and ignore the completion handler.

[application openURL:url options:@{} completionHandler:nil];
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