How to set UIView size to match parent without constraints programmatically

问题

The problem sounds easy but it is making me crazy. I've created a white view in IB that's called iBag and by constraints it's size depends on screen size.

Now I want create a new UIView programmatically and add as subview to iBag with same size and position by this code

let newView = UIView()
newView.frame =  (frame: CGRect(x: 0, y: 0, width: iBag.frame.width, height: iBag.frame.height))
newView.backgroundColor = UIColor.redColor()
iBag.addSubview(newView)

I also tried bounds but that didn't help. I can use constraints to solve the problem but i want to understand what's wrong.

回答1:

So many answers and nobody is explaining what's wrong.

I will try.

You are setting the frame of newView to your superviews frame before the autolayout engine has started to determine your superviews position and size. So, when you use the superviews frame, you are using its initial frame. Which is not correct in most cases.

You have 3 ways to do it correctly:

Use autolayout constraints for your newView
Set newViews frame in the viewDidLayoutSubviews method. Which is called when the autolayout engine finishes determining the frames actual values. (Note: This method can be called multiple times)
Set an autoresizing mask for newView

回答2:

Try this:

Swift 1 and 2:

newView.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

Swift 3+:

newView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

If it doesn't work, also this:

iBag.autoresizesSubviews = true

回答3:

Try this

subview.frame = parentView.bounds

subview.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

parentView.addSubview(subview)

回答4:

Try this,

 override func viewDidLayoutSubviews() {


    newView.frame =  (frame: CGRect(x: 0, y: 0, width: iBag.frame.width, height: iBag.frame.height))

}

or you can use viewWillAppear or viewDidAppear to set frame.

Because in viewDidload your iBag's frame is same which is in your interface builder (storyboard). Now it will change according to your constraints and device size on which you run. So, in viewDidload your new view get old frame not changed frame. So, it's better to use viewDidLayoutSubviews or viewWilAppear.

Second thing, Either use autolayout everywhere or nowhere. It is bad practice to use autolayout in parent view and not to child.

回答5:

May be this will help you

override func viewDidLayoutSubviews() {

    let newView = UIView()
    newView.frame = iBag.bounds
    newView.addConstraints(iBag.constraints)
    newView.backgroundColor = UIColor.redColor()
    iBag.addSubview(newView)

}

Hope this will help you.

回答6:

may be this will work:-

subview.bounds.size = parentView.bounds.size

subview.center = parentView.center

but in your case, width and height inside the CGRect should be

width: parentView.bounds.size.width
height: parentView.bounds.size.height

and then add to it's parent as subview.

回答7:

try this code:

let newView = UIView()
newView.frame =  (frame: CGRect(x: iBag.frame.origin.x, y: iBag.frame.origin.y, width: iBag.frame.size.width, height:  iBag.frame.size.height))
newView.backgroundColor = UIColor.redColor()
iBag.addSubview(newView)

回答8:

Not using constraints is likely what's wrong. If your storyboard/nib is set to use AutoLayout (which is on by default) then setting frames/bounds gets overridden by the AutoLayout system and you HAVE TO use constraints to get your layout to look right. (or set the flag that converts auto resizing masks to constraints. I don't remember what that flag is called and can't seem to find it at the moment.)

回答9:

If you are setting up your view in viewdidload, call it in viewdidappear, so it captures the original frame of view, accordingly to the screen size

来源：https://stackoverflow.com/questions/37725406/how-to-set-uiview-size-to-match-parent-without-constraints-programmatically

标签

ios

swift

uiview

cgrect