Create UIButtons dynamically with for loop in Swift

Question

I am trying to add buttons dynamically to a scroll view after pressing another button.

I created a custom UIView which I want to add to the scroll view.

Below you can find the code how I am trying to do it:

var buttonY: CGFloat = 0  // our Starting Offset, could be 0
            for _ in audioCommentsArray {
                UIView.animateWithDuration(0.15, animations: {

                    let commentView = AudioCommentView(frame: CGRectZero)
                    commentView.frame = CGRect(x: 0, y: buttonY, width: 75, height: 75)

                    buttonY = buttonY + 75  // we are going to space these UIButtons 75px apart

                    commentView.alpha = 1.0

                    audioCommentsListScrollView.addSubview(commentView)
                })
            }

I want to add these commentView's using a simple animation. However only the last commentView is added correctly to the scrollView whereas the above views are added like this:

Only the background of the commentView is shown whereas the other elements are not visible.

Does anyone have an idea what I might be missing? Adding views using a for loop shouldn't be complicated as I have done this many times before but this time I seem to miss something?

Thank you in advance!

I'm trying to understand why you loop for a UIView animation and you did not use a keyframe animation first. Did you intend that one view shows and the next one after 0.15 seconds? — gwinyai
– gwinyai, Commented Nov 28, 2016 at 20:20

gwinyai · Accepted Answer · 2016-11-28 21:18:21Z

1

The UIView animations are overlapping and interfering with each other as you process them through the loop. Instead, you should chain them so that the next animation does not interfere with the other. Delete the loop. Then call the animations one after the other in the completion handler. You can call it recursively to ensure each button is animated.

    var count = 0

    func startButtonsAnimation() {

    UIView.animateWithDuration(0.15, animations: {

                let commentView = AudioCommentView(frame: CGRectZero)
                commentView.frame = CGRect(x: 0, y: buttonY, width: 75, height: 75)

                buttonY = buttonY + 75  // we are going to space these UIButtons 75px apart

                commentView.alpha = 1.0

                audioCommentsListScrollView.addSubview(commentView)
            }, completion: { (value: Bool) in 
                      if self.count < self.audioCommentsArray.count { 
                           self.count += 1
                           self.startButtonsAnimation()
                      }
    })

edited Nov 28, 2016 at 21:18

answered Nov 28, 2016 at 20:43

gwinyai

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2 Comments

Granit Over a year ago

Your solutions seems to work if I want to add the buttons statically, but how do i chain them depending on the number of elements I originally have in my audioCommentsArray? @gwinyai

gwinyai Over a year ago

Sorry. I forgot about that. I have added the code to a function. Each animation is chained but the next is called recursively and it continues until count is equal to the number of elements in your audioCommentsArray.

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