Using @selector in RubyMotion

Question

How do I translate the following method call from ObjectiveC to RubyMotion syntax:

[self.faceView addGestureRecognizer:[
    [UIPinchGestureRecognizer alloc] initWithTarget:self.faceView
    action:@selector(pinch:)]];

I got this far:

self.faceView.addGestureRecognizer(
  UIPinchGestureRecognizer.alloc.initWithTarget(
  self.faceView, action:???))

I understand the @selector(pinch:) indicates a delegation to the receiver object pinch method, but how would I do this in RubyMotion? Maybe using a block?

score 26 · Accepted Answer · answered May 07 '12 at 17:34

26

You should be able to just use a string to specify the selector:

self.faceView.addGestureRecognizer(
  UIPinchGestureRecognizer.alloc.initWithTarget(
  self.faceView, action:'pinch'))

answered May 07 '12 at 17:34

Dylan Markow

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6

The introductory video at Pragmatic Studios covers this, and shows a couple good examples of migrating Obj-C code to ruby: http://pragmaticstudio.com/screencasts/rubymotion – Dylan Markow May 07 '12 at 17:36
4

I'm guessing your pinch action will actually look like this: 'def pinch(recognizer)' which means your selector will actually be 'pinch:' – Jaco Pretorius Feb 16 '13 at 18:09
8

As @JacoPretorius points out, if the target method takes an argument, your selector string must end with a colon `("pinch:")`. – Ben Sheldon Apr 22 '13 at 17:35

score 1 · Answer 2 · answered Mar 04 '18 at 08:40

@gesture = UIPinchGestureRecognizer.alloc.initWithTarget(self.faceView,action:'pinch:')

self.faceView.addGestureRecognizer(@gesture)

def pinch(foo)

end

If you don't want the method handler to take an argument, use action:'pinch' instead. It will then look for a method like this:

def pinch

end

Using an instance var (@gesture = ...) is a good idea here because sometimes gesture recognizers and the GC don't play well together if you don't make the gesture var an instance var of a UIViewController. (In my experience)

Using @selector in RubyMotion

2 Answers2