在我的应用程序的某些时候,我有一个突出显示的UIButton(例如当用户有他的手指在按钮上),我需要改变背景颜色,而按钮是突出显示的(所以当用户的手指仍然在按钮上)。

我尝试了以下方法:

_button.backgroundColor = [UIColor redColor];

但这并不奏效。颜色保持不变。当按钮没有高亮显示时,我尝试了同一段代码,它工作得很好。我还尝试在改变颜色后调用-setNeedsDisplay,它没有任何效果。

如何强制按钮改变背景颜色?


当前回答

斯威夫特3:

extension UIButton {
    private func imageWithColor(color: UIColor) -> UIImage {
        let rect = CGRect(x:0.0,y:0.0,width: 1.0,height: 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()

        context!.setFillColor(color.cgColor)
        context!.fill(rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image!
    }

    func setBackgroundColor(color: UIColor, forUIControlState state: UIControlState) {
        self.setBackgroundImage(imageWithColor(color: color), for: state)
    }
}

其他回答

斯威夫特3:

extension UIButton {
    private func imageWithColor(color: UIColor) -> UIImage {
        let rect = CGRect(x:0.0,y:0.0,width: 1.0,height: 1.0)
        UIGraphicsBeginImageContext(rect.size)
        let context = UIGraphicsGetCurrentContext()

        context!.setFillColor(color.cgColor)
        context!.fill(rect)

        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return image!
    }

    func setBackgroundColor(color: UIColor, forUIControlState state: UIControlState) {
        self.setBackgroundImage(imageWithColor(color: color), for: state)
    }
}

你可以使用这个类别添加方法setBackgroundColor:forState:

https://github.com/damienromito/UIButton-setBackgroundColor-forState-

你可以重写UIButton的setHighlighted方法。

objective - c

- (void)setHighlighted:(BOOL)highlighted {
    [super setHighlighted:highlighted];

    if (highlighted) {
        self.backgroundColor = UIColorFromRGB(0x387038);
    } else {
        self.backgroundColor = UIColorFromRGB(0x5bb75b);
    }
}

Swift 3.0和Swift 4.1

override open var isHighlighted: Bool {
    didSet {
        backgroundColor = isHighlighted ? UIColor.black : UIColor.white
    }
}
extension UIButton {
    func setBackgroundColor(color: UIColor, forState: UIControl.State) {
        let size = CGSize(width: 1, height: 1)
        UIGraphicsBeginImageContext(size)
        let context = UIGraphicsGetCurrentContext()
        context?.setFillColor(color.cgColor)
        context?.fill(CGRect(origin: CGPoint.zero, size: size))
        let colorImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        setBackgroundImage(colorImage, for: forState)
    }

}

谢谢@Maverick

子类化UIButton并添加可检查的属性以方便使用(在Swift 3.0中编写):

final class SelectableBackgroundButton: UIButton {

    private struct Constants {
        static let animationDuration: NSTimeInterval = 0.1
    }

    @IBInspectable
    var animatedColorChange: Bool = true

    @IBInspectable
    var selectedBgColor: UIColor = UIColor.blackColor().colorWithAlphaComponent(0.2)

    @IBInspectable
    var normalBgColor: UIColor = UIColor.clearColor()

    override var selected: Bool {
        didSet {
            if animatedColorChange {
                UIView.animateWithDuration(Constants.animationDuration) {
                    self.backgroundColor = self.selected ? self.selectedBgColor : self.normalBgColor
                }
            } else {
                self.backgroundColor = selected ? selectedBgColor : normalBgColor
            }
        }
    }

    override var highlighted: Bool {
        didSet {
            if animatedColorChange {
                UIView.animateWithDuration(Constants.animationDuration) {
                    self.backgroundColor = self.highlighted ? self.selectedBgColor : self.normalBgColor
                }
            } else {
                self.backgroundColor = highlighted ? selectedBgColor : normalBgColor
            }
        }
    }
}