I have UICollectionViewCell with UIView called gradientView that is used as a background for labels on it.
This UIView needs to have gradient - it is light and almost transparent at the top of cell and becomes slightly darker in the bottom of the cell (simple linear gradient).
So I created func called addGradient that takes UIView and adds layer with gradient to it.
func addGradient(view : UIView){
view.backgroundColor = .clear
let color1 = somecolor1.cgColor
let color2 = somecolor2.cgColor
let gradient:CAGradientLayer = CAGradientLayer()
gradient.frame.size = view.frame.size
gradient.colors = [color1, color2]
view.layer.addSublayer(gradient)
}
Inside cellForItemAt I call addGradient(cell.gradientView) and the gradient is shown. But I have 2 problems:
1) each cell becomes darker and darker - it seems that layers are added one over another and I don't want it
2) sometimes this gradients are slighly misplaced - I also think that is because I don't delete this layers properly
So how and where I should clear sublayers and maybe my method of adding this gradient inside cellForItemAt is not right?
just a guess on number 1 without seeing more of your code: change frame to bounds
func addGradient(view : UIView){
view.backgroundColor = .clear
let color1 = somecolor1.cgColor
let color2 = somecolor2.cgColor
let gradient:CAGradientLayer = CAGradientLayer()
gradient.frame.size = view.bounds.size
gradient.colors = [color1, color2]
view.layer.addSublayer(gradient)
}
Related
I use a simple subclass for UIStackView to add background color for it:
func backgroundColor(_ color: UIColor?) {
backgroundView.backgroundColor = color
}
func cornerRadius(_ radius: CGFloat) {
backgroundView.clipsToBounds = true
backgroundView.layer.cornerRadius = radius
}
The problem is that corner radius using custom view as a container, won't mask arrangedSubviews. I was trying to fix that by overriding addArrangedSubview method:
override func addArrangedSubview(_ view: UIView) {
super.addArrangedSubview(view)
view.mask = backgroundView
}
But it makes weird things and spamming to console:
- changing property mask in
transform-only layer, will have no effect
Instead of adding background to stack view, you can add stack view as a child to the background and mask background with corners.
let wrapper = UIView() // Creating background
wrapper.layer.cornerRadius = 10
wrapper.layer.masksToBounds = true
wrapper.backgroundColor = .yellow
let stack = UIStackView() // Creating stack
stack.frame = wrapper.bounds
stack.autoresizingMask = [.flexibleWidth, .flexibleHeight]
wrapper.addSubview(stack)
I am working on a project that would result in this desired effect:
I am successfully drawing my circle using the following code:
let circle = CircleView()
circle.translatesAutoresizingMaskIntoConstraints = false
circle.backgroundColor = UIColor.clear
self.addSubview(circle)
// Setup constraints
circle.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
circle.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true
circle.widthAnchor.constraint(equalTo: self.widthAnchor, multiplier: 0.6).isActive = true
circle.heightAnchor.constraint(equalTo: circle.widthAnchor, multiplier: 1.0/1.0).isActive = true
For reference, this is my CircleView class:
class CircleView: UIView {
override func draw(_ rect: CGRect) {
// Set the path
let path = UIBezierPath(ovalIn: rect)
// Set the fill color
UIColor.black.setFill()
// Fill
path.fill()
}
}
Subsequently, I am then creating my UILabel, as such:
let myLabel = UILabel()
myLabel.translatesAutoresizingMaskIntoConstraints = false
myLabel.text = "HELLO"
myLabel.textColor = UIColor.white
circle.addSubview(myLabel)
// Setup constraints
myLabel.centerXAnchor.constraint(equalTo: circle.centerXAnchor).isActive = true
myLabel.centerYAnchor.constraint(equalTo: circle.centerYAnchor).isActive = true
I have attempted to mask my circle by using:
circle.mask = myLabel
This, however, results in the opposite effect I am after (my text is not a cut-out in the UIView, but rather, my text is now black). Where might I be going wrong to accomplish this effect?
Masks work in an opposite fashion, when the color on your mask is not transparent then it will show the content in that pixels position and when the pixels are transparent then it will hide the content.
Since you can't achieve this using UILabel you need to use something else as a mask, such as a CALayer.
If you lookup "UILabel see through text" you should find results similar to this which basically also applies to you (with some changes).
Instantiate your CircleView, then instantiate a CATextLayer and use this as a mask for your UIView
Can;t figure out the answer yet, but I have this code which is called for a view:
func gradient(fillView view: NSView, withGradientFromColors colors: Array<NSColor>) {
let gradientLayer = CAGradientLayer()
gradientLayer.frame = view.bounds
let color1 = colors[0].cgColor
let color2 = colors[1].cgColor
gradientLayer.colors = [color1, color2]
gradientLayer.locations = [0.0, 1.0]
view.layer?.addSublayer(gradientLayer)
This code takes two values of NSColor and should create a gradient background.
The code works! Buut, if i try to execute something else on this view for example i have a label on top of it which needs to be shown, it's actually not shown after this code is executed. I believe it is somehow behind the view that i draw?
Any fast way of resolving this issue?
Change the adding of sublayer as below:
view.layer?.insertSublayer(gradientLayer, at: 0)
I've got a UILabel is using a border the same color as a background which it is half obscuring, to create a nice visual effect. However the problem is that there is still a tiny, yet noticeable, sliver of the label's background color on the OUTSIDE of the border.
The border is not covering the whole label!
Changing the border width doesn't change anything either, sadly.
Here's a picture of what's going on, enlarged so you can see it:
And my code follows:
iconLbl.frame = CGRectMake(theWidth/2-20, bottomView.frame.minY-20, 40, 40)
iconLbl.font = UIFont.fontAwesomeOfSize(23)
iconLbl.text = String.fontAwesomeIconWithName(.Info)
iconLbl.layer.masksToBounds = true
iconLbl.layer.cornerRadius = iconLbl.frame.size.width/2
iconLbl.layer.borderWidth = 5
iconLbl.layer.borderColor = topBackgroundColor.CGColor
iconLbl.backgroundColor = UIColor.cyanColor()
iconLbl.textColor = UIColor.whiteColor()
Is there something I'm missing?
Or am I going to have to figure out another to achieve this effect?
Thanks!
EDIT:
List of things I've tried so far!
Changing layer.borderWidth
Fussing around with clipsToBounds/MasksToBounds
Playing around the the layer.frame
Playing around with an integral frame
EDIT 2:
No fix was found! I used a workaround by extending this method on to my UIViewController
func makeFakeBorder(inputView:UIView,width:CGFloat,color:UIColor) -> UIView {
let fakeBorder = UIView()
fakeBorder.frame = CGRectMake(inputView.frame.origin.x-width, inputView.frame.origin.y-width, inputView.frame.size.width+width*2, inputView.frame.size.height+width*2)
fakeBorder.backgroundColor = color
fakeBorder.clipsToBounds = true
fakeBorder.layer.cornerRadius = fakeBorder.frame.size.width/2
fakeBorder.addSubview(inputView)
inputView.center = CGPointMake(fakeBorder.frame.size.width/2, fakeBorder.frame.size.height/2)
return fakeBorder
}
I believe this is the way a border is drawn to a layer in iOS. In the document it says:
When this value is greater than 0.0, the layer draws a border using the current borderColor value. The border is drawn inset from the receiver’s bounds by the value specified in this property. It is composited above the receiver’s contents and sublayers and includes the effects of the cornerRadius property.
One way to fix this is to apply a mask to a view's layer, but I found out that even if so we still can see a teeny tiny line around the view when doing snapshot tests. So to fix it more, I put this code to layoutSubviews
class MyView: UIView {
override func layoutSubviews() {
super.layoutSubviews()
let maskInset: CGFloat = 1
// Extends the layer's frame.
layer.frame = layer.frame.inset(dx: -maskInset, dy: -maskInset)
// Increase the border width
layer.borderWidth = layer.borderWidth + maskInset
layer.cornerRadius = bounds.height / 2
layer.maskToBounds = true
// Create a circle shape layer with true bounds.
let mask = CAShapeLayer()
mask.path = UIBezierPath(ovalIn: bounds.inset(dx: maskInset, dy: maskInset)).cgPath
layer.mask = mask
}
}
CALayer's mask
Given an arbitrary UIView on iOS, is there a way using Core Graphics (CAGradientLayer comes to mind) to apply a "foreground-transparent" gradient to it?
I can't use a standard CAGradientLayer because the background is more complex than a UIColor. I also can't overlay a PNG because the background will change as my subview is scrolled along its parent vertical scrollview (see image).
I have a non-elegant fallback: have my uiview clip its subviews and move a pre-rendered gradient png of the background as the parent scrollview is scrolled.
This was an embarrassingly easy fix: apply a CAGradientLayer as my subview's mask.
CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.frame = _fileTypeScrollView.bounds;
gradientLayer.colors = [NSArray arrayWithObjects:(id)[UIColor whiteColor].CGColor, (id)[UIColor clearColor].CGColor, nil];
gradientLayer.startPoint = CGPointMake(0.8f, 1.0f);
gradientLayer.endPoint = CGPointMake(1.0f, 1.0f);
_fileTypeScrollView.layer.mask = gradientLayer;
Thanks to Cocoanetics for pointing me in the right direction!
This is how I'll do.
Step 1 Define a custom gradient view (Swift 4):
import UIKit
class GradientView: UIView {
override open class var layerClass: AnyClass {
return CAGradientLayer.classForCoder()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
let gradientLayer = self.layer as! CAGradientLayer
gradientLayer.colors = [
UIColor.white.cgColor,
UIColor.init(white: 1, alpha: 0).cgColor
]
backgroundColor = UIColor.clear
}
}
Step 2 - Drag and drop a UIView in your storyboard and set its custom class to GradientView
As an example, this is how the above gradient view looks like:
https://github.com/yzhong52/GradientViewDemo
I used the accepted (OP's) answer above and ran into the same issue noted in an upvoted comment - when the view scrolls, everything that started offscreen is now transparent, covered by the mask.
The solution was to add the gradient layer as the superview's mask, not the scroll view's mask. In my case, I'm using a text view, which is contained inside a view called contentView.
I added a third color and used locations instead of startPoint and endPoint, so that items below the text view are still visible.
let gradientLayer = CAGradientLayer()
gradientLayer.frame = self.contentView!.bounds
gradientLayer.colors = [UIColor.white.cgColor, UIColor.clear.cgColor, UIColor.white.cgColor]
// choose position for gradient, aligned to bottom of text view
let bottomOffset = (self.textView!.frame.size.height + self.textView!.frame.origin.y + 5)/self.contentView!.bounds.size.height
let topOffset = bottomOffset - 0.1
let bottomCoordinate = NSNumber(value: Double(bottomOffset))
let topCoordinate = NSNumber(value: Double(topOffset))
gradientLayer.locations = [topCoordinate, bottomCoordinate, bottomCoordinate]
self.contentView!.layer.mask = gradientLayer
Before, the text that started offscreen was permanently invisible. With my modifications, scrolling works as expected, and the "Close" button is not covered by the mask.
I just ran into the same issue and wound up writing my own class. It seems like serious overkill, but it was the only way I could find to do gradients with transparency. You can see my writeup and code example here
It basically comes down to a custom UIView that creates two images. One is a solid color, the other is a gradient that is used as an image mask. From there I applied the resulting image to the uiview.layer.content.
I hope it helps,
Joe
I hate to say it, but I think that you are into the CUSTOM UIView land. I think that I would try to implement this in a custom UIView overiding the drawRect routine.
With this, you could have that view, place on top of your actual scrollview, and have your gradient view (if you will) "pass-on" all touch events (i.e. relinquish first responder).