How to give “locations” to CAGradientLayer

问题:

I have created CAGradientLayer having three colors, i need to give each color different locations. Example:

Red = 0 to 50 %
Yellow = 51 to 80 %
Green = 81 to 100 %

I have tried with giving startPoint and endPoint but it did not work.

回答1:

If you put the following code into a Playground you will get the exact desired output:

let view = UIView(frame: CGRectMake(0,0,200,100))

let layer = CAGradientLayer()
layer.frame = view.frame
layer.colors = [UIColor.greenColor().CGColor, UIColor.yellowColor().CGColor, UIColor.redColor().CGColor]
layer.locations = [0.0, 0.8, 1.0]

view.layer.addSublayer(layer)

XCPShowView("ident", view: view)

Outputting:

You simply define the colors as an array of CGColors, and an array of the same size of NSNumbers each between 0.0 and 1.0.

Dont use startPoint and endPoint for that - they are for defining from where to where the gradient is shown in the layer - it does not have anything to do with the percents and the colors etc.

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More recent Swift3 version of the code:

let view = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 100))
let layer = CAGradientLayer()
layer.frame = view.frame
layer.colors = [UIColor.green.cgColor, UIColor.yellow.cgColor, UIColor.red.cgColor]
layer.locations = [0.0, 0.8, 1.0]
view.layer.addSublayer(layer)
PlaygroundPage.current.liveView = view