How to use frame to set x position in loop on Swift

问题

I have an array that count is between 1 to 3 varies. I want to frame them in the middle of the screen with a certain distance Also the width of the labels is fixed

let array = ["some1", "some2", "some3"]

func setLabel(){
  var i = -1
  for text in array{
      i += 1
      let label = UILabel()
      label.fram = CGRect(x: screenWidth/2 - (CGFloat(i)*50) + 25, y: 100, width: 50 , height: 20)
      label.text = text
      addSubview(label)
  }
}

回答1:

You can use stackview as suggested by @matt. If you don't want to use stackview you can calculate the x position by array count and label index like this

let array = ["some1", "some2", "some3"]
func setLabel(){
    var i:CGFloat = 0
    for text in array{
        i += 1
        let label = UILabel()
        label.backgroundColor = .red
        label.frame = CGRect(x: (view.bounds.width/CGFloat(array.count+1))*i-25, y: 100, width: 50 , height: 20)
        label.text = text
        view.addSubview(label)
    }
}

回答2:

The really easy way to do this is to put the labels (one, two, or three of them) into a centered UIStackView. You would still need to know the desired fixed width of a label and apply a width constraint to each label, but everything else will just take care of itself.

Just as a demonstration, I used an arbitrary width of 100, with the text for all three labels being just "UILabel" as in your image. Here's what it looks like with one label:

Here's what it looks like with three labels:

Here's the code I used (sv is the stack view, which has already been configured in the storyboard; n is how many labels we want):

    for _ in 1...n {
        let lab = UILabel()
        lab.text = "UILabel"
        lab.textAlignment = .center
        lab.translatesAutoresizingMaskIntoConstraints = false
        lab.widthAnchor.constraint(equalToConstant: 100).isActive = true
        sv.addArrangedSubview(lab)
    }

So all you really need to do is get the right text from your array as we loop, and you're done. The point is that you don't need to think about frames at all! The UIStackView imposes the correct the frames for us.

NOTE Although I said above that the stack view was "configured in the storyboard", that has nothing to do with the answer. You can create and configure the stack view in code just as well, without changing anything about my answer. The point is that the stack view already knows how to receive an arbitrary number of views, space them out evenly, and center them as a whole. That is what it is for. So if, as your question implies, you can't manage the arithmetic to assign the views a frame yourself, why not let the stack view do it for you?

来源：https://stackoverflow.com/questions/56386677/how-to-use-frame-to-set-x-position-in-loop-on-swift

标签

swift

frame