Swift绘制渐变色的方法

本文实例为大家分享了Swift绘制渐变色的具体代码，供大家参考，具体内容如下

示意图：

import Foundation
import UIKit

class GradientVC: UIViewController {

    @IBOutlet weak var butOne: GradientCustomButton!
    @IBOutlet weak var viewTwo: UIView!

    override func viewDidLoad() {
        super.viewDidLoad()

        /// 方式一 xib添加渐变色

        /// 方式一 代码添加渐变色
        butOne.isGradient = true
        butOne.startColor = UIColor(hexString: "#FD0134")!
        butOne.endColor = UIColor(hexString: "#007AFF")!
        butOne.startPoint = CGPoint(x: 0,y: 0)
        butOne.endPoint = CGPoint(x: 1,y: 1)

        /// 方式二
        //viewTwo.addGradient(start_color: "#8238FF", end_color: "#007AFF")
        //viewTwo.layer.masksToBounds = true
        viewTwo.addGradient(colors: [UIColor(hexString: "#FD0134")!, UIColor(hexString: "#007AFF")!],
                            point: (CGPoint(x: 1.0, y: 0.0), CGPoint(x: 0.0, y: 1.0)),
                            frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width-40, height: 100),
                            radius: 0)

    }
}

方式一：

使用xib或代码的方式添加渐变色.

这种方式有个缺点, 若是要对更多的视图(比如UILabel)添加渐变色, 需要继续创建一个子类继承于它进行功能的拓展.

import Foundation
import UIKit

class GradientCustomView: UIView {

    @IBInspectable var isGradient: Bool = false
    @IBInspectable var startColor: UIColor = .white
    @IBInspectable var endColor: UIColor = .white
    @IBInspectable var locations: [NSNumber] = [0 , 1]
    @IBInspectable var startPoint: CGPoint = .zero
    @IBInspectable var endPoint: CGPoint = .zero

    private var gradientBGLayer: CAGradientLayer?

    override func layoutSubviews() {
        super.layoutSubviews()
        gradientBGLayer?.removeFromSuperlayer()
        if isGradient {
            gradientBGLayer = CAGradientLayer()
            gradientBGLayer!.colors = [startColor.cgColor, endColor.cgColor]
            gradientBGLayer!.locations = locations
            gradientBGLayer!.frame = bounds
            gradientBGLayer!.startPoint = startPoint
            gradientBGLayer!.endPoint = endPoint
            self.layer.insertSublayer(gradientBGLayer!, at: 0)
        }
    }

}

class GradientCustomButton: UIButton {

    @IBInspectable var isGradient: Bool = false
    @IBInspectable var startColor: UIColor = .white
    @IBInspectable var endColor: UIColor = .white
    @IBInspectable var locations: [NSNumber] = [0 , 1]
    @IBInspectable var startPoint: CGPoint = .zero
    @IBInspectable var endPoint: CGPoint = .zero

    private var gradientBGLayer: CAGradientLayer?

    override func layoutSubviews() {
        super.layoutSubviews()
        gradientBGLayer?.removeFromSuperlayer()
        if isGradient {
            gradientBGLayer = CAGradientLayer()
            gradientBGLayer!.colors = [startColor.cgColor, endColor.cgColor]
            gradientBGLayer!.locations = locations
            gradientBGLayer!.frame = bounds
            gradientBGLayer!.startPoint = startPoint
            gradientBGLayer!.endPoint = endPoint
            self.layer.insertSublayer(gradientBGLayer!, at: 0)
        }
    }

}

方式二：

直接拓展UIView,让每个继承于UIView的视图都可以调用拓展的方法.

这种方式的缺点就是无法在Xib中使用

import Foundation
import UIKit

extension UIView {

    @discardableResult
    func addGradient(colors: [UIColor],
                     point: (CGPoint, CGPoint) = (CGPoint(x: 0.5, y: 0), CGPoint(x: 0.5, y: 1)),
                     locations: [NSNumber] = [0, 1],
                     frame: CGRect = CGRect.zero,
                     radius: CGFloat = 0,
                     at: UInt32 = 0) -> CAGradientLayer {
        let bgLayer1 = CAGradientLayer()
        bgLayer1.colors = colors.map { $0.cgColor }
        bgLayer1.locations = locations
        if frame == .zero {
            bgLayer1.frame = self.bounds
        } else {
            bgLayer1.frame = frame
        }
        bgLayer1.startPoint = point.0
        bgLayer1.endPoint = point.1
        bgLayer1.cornerRadius = radius
        self.layer.insertSublayer(bgLayer1, at: at)
        return bgLayer1
    }

    func addGradient(start: CGPoint = CGPoint(x: 0.5, y: 0),
                     end: CGPoint = CGPoint(x: 0.5, y: 1),
                     colors: [UIColor],
                     locations: [NSNumber] = [0, 1],
                     frame: CGRect = CGRect.zero,
                     radius: CGFloat = 0,
                     at: UInt32 = 0) {
        let bgLayer1 = CAGradientLayer()
        bgLayer1.colors = colors.map { $0.cgColor }
        bgLayer1.locations = locations
        bgLayer1.frame = frame
        bgLayer1.startPoint = start
        bgLayer1.endPoint = end
        bgLayer1.cornerRadius = radius
        self.layer.insertSublayer(bgLayer1, at: at)
    }

    func addGradient(start_color:String,end_color : String,frame : CGRect?=nil,cornerRadius : CGFloat?=0, at: UInt32 = 0){
        var bounds : CGRect = self.bounds
        if let frame = frame {
            bounds = frame
        }
        let bgLayer1 = CAGradientLayer()
        bgLayer1.colors = [UIColor(hexString: start_color)!.cgColor, UIColor(hexString: end_color)!.cgColor]
        bgLayer1.locations = [0, 1]
        bgLayer1.frame = bounds
        bgLayer1.startPoint = CGPoint(x: 0, y: 0.61)
        bgLayer1.endPoint = CGPoint(x: 0.61, y: 0.61)
        bgLayer1.cornerRadius = cornerRadius ?? 0
        self.layer.insertSublayer(bgLayer1, at: at)
    }

    func addGradient(start_color:String,
                     end_color : String,
                     frame : CGRect?=nil,
                     borader: CGFloat = 0,
                     boraderColor: UIColor = .clear,
                     at: UInt32 = 0,
                     corners: UIRectCorner?,
                     radius: CGFloat = 0) {
        var bounds : CGRect = self.bounds
        if let frame = frame {
            bounds = frame
        }
        let bgLayer1 = CAGradientLayer()
        bgLayer1.colors = [UIColor(hexString: start_color)!.cgColor, UIColor(hexString: end_color)!.cgColor]
        bgLayer1.locations = [0, 1]
        bgLayer1.frame = bounds
        bgLayer1.startPoint = CGPoint(x: 0, y: 0.61)
        bgLayer1.endPoint = CGPoint(x: 0.61, y: 0.61)
        bgLayer1.borderColor = boraderColor.cgColor
        bgLayer1.borderWidth = borader
        if corners != nil {
            let cornerPath = UIBezierPath(roundedRect: bounds, byRoundingCorners: corners!, cornerRadii: CGSize(width: radius, height: radius))
            let radiusLayer = CAShapeLayer()
            radiusLayer.frame = bounds
            radiusLayer.path = cornerPath.cgPath
            bgLayer1.mask = radiusLayer
        }
        self.layer.insertSublayer(bgLayer1, at: at)
    }

    func addGradient(startPoint: CGPoint = CGPoint(x: 0, y: 0.5),
                     start_color:String,
                     endPoint: CGPoint = CGPoint(x: 1, y: 0.5),
                     end_color : String,
                     frame : CGRect? = nil,
                     cornerRadius : CGFloat?=0){
        var bounds : CGRect = self.bounds
        if let frame = frame {
            bounds = frame
        }
        let bgLayer1 = CAGradientLayer()
        bgLayer1.frame = bounds
        bgLayer1.startPoint = startPoint
        bgLayer1.endPoint = endPoint
        bgLayer1.colors = [UIColor(hexString: start_color)!.cgColor, UIColor(hexString: end_color)!.cgColor]
        bgLayer1.locations = [0, 1]
        bgLayer1.cornerRadius = cornerRadius ?? 0
        self.layer.addSublayer(bgLayer1)
    }

    func addVerticalGradient(start_color:String,end_color : String,frame : CGRect?=nil,cornerRadius : CGFloat?=0){
        var bounds : CGRect = self.bounds
        if let frame = frame {
            bounds = frame
        }
        let bgLayer1 = CAGradientLayer()
        bgLayer1.colors = [UIColor(hexString: start_color)!.cgColor, UIColor(hexString: end_color)!.cgColor]
        bgLayer1.locations = [0, 1]
        bgLayer1.frame = bounds
        bgLayer1.startPoint = CGPoint(x: 0.5, y: 0)
        bgLayer1.endPoint = CGPoint(x: 1, y: 1)
        bgLayer1.cornerRadius = cornerRadius ?? 0
        self.layer.insertSublayer(bgLayer1, at: 0)
    }

    //将当前视图转为UIImage
    func asImage() -> UIImage {
        let renderer = UIGraphicsImageRenderer(bounds: bounds)
        return renderer.image { rendererContext in
            layer.render(in: rendererContext.cgContext)
        }
    }
}

Demo：绘制渐变色

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