Calling a method on the main thread?

Question

First of all I am writing code for iphone. I need to be able to call a method on the main thread without using performSelectorOnMainThread. The reason that I don't want to use performSelectorOnMainThread is that it causes problem when I am trying to create a mock for unit testing.

[self performSelectorOnMainThread:@Selector(doSomething) withObject:nil];

The problem is that my mock knows how to call doSomething but it doesn't know how to call performSelectorOnMainThread.

So Any solution?

Answer 1

Objective-C

dispatch_async(dispatch_get_main_queue(), ^{
  [self doSomething];
});

Swift

dispatch_async(dispatch_get_main_queue()) {
   self.doSomething()
}

Swift 3 and 4

DispatchQueue.main.async {
   self.doSomething()
}

Answer 2

There's a saying in software that adding a layer of indirection will fix almost anything.

Have the doSomething method be an indirection shell that only does a performSelectorOnMainThread to call the really_doSomething method to do the actual Something work. Or, if you don't want to change your doSomething method, have the mock test unit call a doSomething_redirect_shell method to do something similar.

Answer 3

Here is a better way to do this in Swift:

runThisInMainThread { () -> Void in
    // Run your code
    self.doSomething()
}

func runThisInMainThread(block: dispatch_block_t) {
    dispatch_async(dispatch_get_main_queue(), block)
}

Its included as a standard function in my repo, check it out: https://github.com/goktugyil/EZSwiftExtensions

Answer 4

And now in Swift 3:

DispatchQueue.main.async{
   self.doSomething()
}