How to set UIView size to match parent without constraints programmatically

Question

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.

Gown

Where are you instantiating the new view in ViewWillAppear ??? – Electrograph

@SandeepBhandari In viewDidLoad – Gown

Can you try it in ViewDidAppear ???? – Electrograph

Use the code in viewWillAppear or viewDidAppear. – Rarebit

This is because of constrains. – Maenad

You should add the new view in viewDidLayoutSubviews as the frame & autolayout process won't be complete before then. Make sure you keep a reference to your new view and only add it if this is nil as viewDidLayoutSubviews may be called more than once – Hiltan

set the new view's constraints programmatically too, then it will work – Dinner

@Paulw11Thank You. That's right.I should have known the issue. – Gown

Answer 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

Hillery

Thank you. You saved my weekend. All tutorials tells how to format UIView and no one tells that update must be called on viewDidLayoutSubviews instead of viewDidLoad – Lucent

Answer 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

Corey

Answer 3

Try this

subview.frame = parentView.bounds

subview.autoresizingMask = [.FlexibleWidth, .FlexibleHeight]

parentView.addSubview(subview)

Pemberton

Answer 4

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.

Christopherchristopherso

Sorry but still no result – Gown

Are you using auto resize in storyboard or constraints layout? – Christopherchristopherso

After trying different things it worked but it only works in viewDidLayoutSubviews function. Anyway Thank you. – Gown

Answer 5

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.

Hildie

That is not a good solution because viewDidLayoutSubviews is called multiple times. So there will be many "newViews" created. – Acescent

yeah that's right @Acescent Edited my answer! Now, it is fine i think – Hildie

Answer 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.

Myrmecophagous

Nope , same result. – Gown

Answer 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)

Weinberg

Answer 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.)

Mcripley

Answer 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

Enthronement

Answer 10

Try use applyConstraints

parentView.addSubview(newSubview, applyConstraints: true)

Circuitous

UIView.addSubview only accepts one parameter according to the documentation: developer.apple.com/documentation/uikit/uiview/… – Luker