在Swift中設置背景漸變

Question

我不知道如何設置按鈕上的背景漸變（不使背景漸變成爲圖像）。這與Android非常不同。

這裏有一個I類必須定義一個可回收梯度方案：

import UIKit 

extension CAGradientLayer { 

    func backgroundGradientColor() -> CAGradientLayer { 
     let topColor = UIColor(red: (0/255.0), green: (153/255.0), blue:(51/255.0), alpha: 1) 
     let bottomColor = UIColor(red: (0/255.0), green: (153/255.0), blue:(255/255.0), alpha: 1) 

     let gradientColors: [CGColor] = [topColor.CGColor, bottomColor.CGColor] 
     let gradientLocations: [Float] = [0.0, 1.0] 

     let gradientLayer: CAGradientLayer = CAGradientLayer() 
     gradientLayer.colors = gradientColors 
     gradientLayer.locations = gradientLocations 

     return gradientLayer 

    } 
} 

我可以用它來設置我的整個觀點有以下背景：

class ViewController: UIViewController { 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let background = CAGradientLayer().backgroundGradientColor() 
     background.frame = self.view.bounds 
     self.view.layer.insertSublayer(background, atIndex: 0) 
    } 
    //... 
} 

但我怎麼能訪問按鈕的視圖並插入子圖層或類似的東西？我搜索了幾個小時，找不到任何有用的東西。我很迷茫。

Answer 1

你的代碼工作正常。你只需要記住每次都設置漸變的框架。最好讓漸變類別爲您設置視圖的框架。

這樣你不會忘記，它適用於罰款。

extension UIView { 
    func applyGradient(colours: [UIColor]) -> Void { 
     self.applyGradient(colours, locations: nil) 
    } 

    func applyGradient(colours: [UIColor], locations: [NSNumber]?) -> Void { 
     let gradient: CAGradientLayer = CAGradientLayer() 
     gradient.frame = self.bounds 
     gradient.colors = colours.map { $0.CGColor } 
     gradient.locations = locations 
     self.layer.insertSublayer(gradient, atIndex: 0) 
    } 
} 

class ViewController: UIViewController { 

    @IBOutlet weak var btn: UIButton! 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     self.btn.titleLabel?.textColor = UIColor.whiteColor() 

     self.btn.applyGradient([UIColor.yellowColor(), UIColor.blueColor()]) 
     self.view.applyGradient([UIColor.yellowColor(), UIColor.blueColor(), UIColor.redColor()], locations: [0.0, 0.5, 1.0]) 
    } 

    override func didReceiveMemoryWarning() { 
     super.didReceiveMemoryWarning() 
    } 
} 

按鈕是視圖。您可以將漸變應用於其中，方法與將其應用於任何其他視圖的方式相同。

Answer 2

這裏下面你可以找到Swift3解決方案，並一點點延長（定向助手）：

typealias GradientPoints = (startPoint: CGPoint, endPoint: CGPoint) 

enum GradientOrientation { 
    case topRightBottomLeft 
    case topLeftBottomRight 
    case horizontal 
    case vertical 

    var startPoint : CGPoint { 
    return points.startPoint 
    } 

    var endPoint : CGPoint { 
    return points.endPoint 
    } 

    var points : GradientPoints { 
    get { 
     switch(self) { 
     case .topRightBottomLeft: 
     return (CGPoint(x: 0.0,y: 1.0), CGPoint(x: 1.0,y: 0.0)) 
     case .topLeftBottomRight: 
     return (CGPoint(x: 0.0,y: 0.0), CGPoint(x: 1,y: 1)) 
     case .horizontal: 
     return (CGPoint(x: 0.0,y: 0.5), CGPoint(x: 1.0,y: 0.5)) 
     case .vertical: 
     return (CGPoint(x: 0.0,y: 0.0), CGPoint(x: 0.0,y: 1.0)) 
     } 
    } 
    } 
} 

extension UIView { 

    func applyGradient(withColours colours: [UIColor], locations: [NSNumber]? = nil) -> Void { 
    let gradient = CAGradientLayer() 
    gradient.frame = self.bounds 
    gradient.colors = colours.map { $0.cgColor } 
    gradient.locations = locations 
    self.layer.insertSublayer(gradient, at: 0) 
    } 

    func applyGradient(withColours colours: [UIColor], gradientOrientation orientation: GradientOrientation) -> Void { 
    let gradient = CAGradientLayer() 
    gradient.frame = self.bounds 
    gradient.colors = colours.map { $0.cgColor } 
    gradient.startPoint = orientation.startPoint 
    gradient.endPoint = orientation.endPoint 
    self.layer.insertSublayer(gradient, at: 0) 
    } 
} 

Answer 3

@Zeb答案是偉大的，但只是把它清理乾淨，並使其多了幾分SWIFTY 。 已計算只讀屬性應該避免使用get和返回void是多餘的：

typealias GradientPoints = (startPoint: CGPoint, endPoint: CGPoint) 

enum GradientOrientation { 
    case topRightBottomLeft 
    case topLeftBottomRight 
    case horizontal 
    case vertical 

var startPoint: CGPoint { 
    return points.startPoint 
} 

var endPoint: CGPoint { 
    return points.endPoint 
} 

var points: GradientPoints { 
    switch self { 
    case .topRightBottomLeft: 
     return (CGPoint.init(x: 0.0, y: 1.0), CGPoint.init(x: 1.0, y: 0.0)) 
    case .topLeftBottomRight: 
     return (CGPoint.init(x: 0.0, y: 0.0), CGPoint.init(x: 1, y: 1)) 
    case .horizontal: 
     return (CGPoint.init(x: 0.0, y: 0.5), CGPoint.init(x: 1.0, y: 0.5)) 
    case .vertical: 
     return (CGPoint.init(x: 0.0, y: 0.0), CGPoint.init(x: 0.0, y: 1.0)) 
    } 
    } 
} 

extension UIView { 

func applyGradient(withColours colours: [UIColor], locations: [NSNumber]? = nil) { 
    let gradient: CAGradientLayer = CAGradientLayer() 
    gradient.frame = self.bounds 
    gradient.colors = colours.map { $0.cgColor } 
    gradient.locations = locations 
    self.layer.insertSublayer(gradient, at: 0) 
} 

func applyGradient(withColours colours: [UIColor], gradientOrientation orientation: GradientOrientation) { 
    let gradient: CAGradientLayer = CAGradientLayer() 
    gradient.frame = self.bounds 
    gradient.colors = colours.map { $0.cgColor } 
    gradient.startPoint = orientation.startPoint 
    gradient.endPoint = orientation.endPoint 
    self.layer.insertSublayer(gradient, at: 0) 
    } 
} 

Answer 4

我已經嘗試了所有的人，這是我的按鈕初始化的viewDidLoad內

let button = UIButton() 
    button.setTitle("Alper", for: .normal) 
    button.layer.borderColor = UIColor.white.cgColor 
    button.layer.borderWidth = 1 
    view.addSubview(button) 
    button.anchor(top: nil, left: nil, bottom: logo.topAnchor, right: nil, paddingTop: 0, paddingLeft: 0, paddingBottom: 0, paddingRight: 0, height: 50, width: 100) 
    let gradientx = CAGradientLayer() 
    gradientx.colors = [UIColor.blue,UIColor.red] 
    gradientx.startPoint = CGPoint(x: 0.0, y: 0.5) 
    gradientx.endPoint = CGPoint(x: 1.0, y: 1.0) 
    gradientx.frame = button.bounds 
    button.layer.insertSublayer(gradientx, at: 0) 

錨是一個擴展，所以這是不相關的漸變。