I'm having trouble with my attempt of objective-c block equivalent in swift

Question

Here is the objective-c code:

options.onPan = ^(MDCPanState *state){
    if (state.thresholdRatio == 1.f && state.direction == MDCSwipeDirectionLeft) {
        NSLog(@"Let go now to delete the photo!");
    }
};

Swift:

   var options = MDCSwipeToChooseViewOptions()
        options.delegate = self
        options.likedText = "Keep"
        options.likedColor = UIColor.blueColor()
        options.nopeText = "Delete"

        options.onPan = { (state: MDCPanState) in
            if state.thresholdRatio == 1.0 && state.direction == MDCSwipeDirection.Left {
                println("Let go now to delete the photo!");
            }
        }

This is throwing an error:

'(MDCPanState) -> (MDCPanState) -> $T2' is not convertible to 'MDCPanState'

Would appreciate some help thanks.

What is the type declaration of options.onPan? The implication of the error message seems to be that the closure needs to return non void. — JeremyP
– JeremyP, Commented Mar 3, 2015 at 16:44
@JeremyP I've updated my answer. The return type is MDCSwipeToChooseViewOptions() — LondonGuy
– LondonGuy, Commented Mar 3, 2015 at 17:14

Steve · Accepted Answer · 2015-03-03 17:47:56Z

1

I'm not 100% since I don't have XCode near me at the moment, but I believe you need to change this:

options.onPan = { (state: MDCPanState) in
        if state.thresholdRatio == 1.0 && state.direction == MDCSwipeDirection.Left {
            println("Let go now to delete the photo!");
        }

to this:

options.onPan = { (state: MDCPanState!) -> Void in
        if state.thresholdRatio == 1.0 && state.direction == MDCSwipeDirection.Left {
            println("Let go now to delete the photo!");
        }

answered Mar 3, 2015 at 17:47

Steve

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3 Comments

Steve Over a year ago

What's weird about the syntax to you?

UKDataGeek Over a year ago

Its seeing the { after the equals sign. I haven't seen this construct before. Can you provide more information or a link to some docs to help understand it? Is it shortened notation?

Steve Over a year ago

you are setting onPan to a completion block and that's the syntax in swift. this may help codefellows.org/blog/…

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