Swift。添加一个渐变到tableview隐藏内容

Question

我有一个tableview，它运作良好。但我必须在背景上添加渐变。我用viewDidLoad中的这段代码做了：

gradientLayer.frame = self.view.bounds 
let color1 = UIColor.blueColor().CGColor as CGColorRef 
let color2 = UIColor.redColor().CGColor as CGColorRef 
gradientLayer.colors = [color1, color2] 
gradientLayer.locations = [0.0, 1.0] 
gradientLayer.startPoint = CGPoint(x: 1, y: 0) 
gradientLayer.endPoint = CGPoint(x: 0, y: 0) 
self.view.layer.addSublayer(gradientLayer) 
self.view.backgroundColor = UIColor.greenColor() 

但是现在我看不到我的tableview的任何内容。

请问有人能帮我一下吗？

Answer 1

要正确配置背景渐变，您可以使用UITableView的backgroundView属性和CAGradientLayer的查看。所得代码（在夫特3）将是：

/* A small UIView subclass displaying gradient */ 

class GradientView: UIView { 

    /* Overriding default layer class to use CAGradientLayer */ 
    override class var layerClass: AnyClass { 
     return CAGradientLayer.self 
    } 

    /* Handy accessor to avoid unnecessary casting */ 
    private var gradientLayer: CAGradientLayer { 
     return layer as! CAGradientLayer 
    } 

    /* Public properties to manipulate colors */ 
    public var fromColor: UIColor = UIColor.red { 
     didSet { 
      var currentColors = gradientLayer.colors 
      currentColors![0] = fromColor.cgColor 
      gradientLayer.colors = currentColors 
     } 
    } 

    public var toColor: UIColor = UIColor.blue { 
     didSet { 
      var currentColors = gradientLayer.colors 
      currentColors![1] = toColor.cgColor 
      gradientLayer.colors = currentColors 
     } 
    } 

    /* Initializers overriding to have appropriately configured layer after creation */ 
    override init(frame: CGRect) { 
     super.init(frame: frame) 
     gradientLayer.colors = [fromColor.cgColor, toColor.cgColor] 
     gradientLayer.startPoint = CGPoint(x: 0, y: 0.5) 
     gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5) 
    } 

    required init?(coder aDecoder: NSCoder) { 
     super.init(coder: aDecoder) 
     gradientLayer.colors = [fromColor.cgColor, toColor.cgColor] 
     gradientLayer.startPoint = CGPoint(x: 0, y: 0.5) 
     gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5) 
    } 
} 


/* Code that should be called in viewDidLoad method */ 

class MyViewController: UITableViewController { 

    /* ... */ 

    override func viewDidLoad() { 
     super.viewDidLoad() 
     tableView.backgroundView = GradientView() 
    } 

    /* ... */ 

}