Swift UIButton覆盖,setImage不起作用

Question

我正在尝试UIButton使用我自己的按钮类进行子类化FlipsSendButton.下面列出了此类的代码.在其中你可以看到我打电话setImage试图设置按钮图像.但是,编译后,除了设置图像视图外,一切正常.

我错过了我的代码中的一些步骤来设置图像,或者可能错误地调用可选和解包操作符？

import Foundation

class FlipSendButton : UIButton {

    let bgColor : UIColor

    init(frame aFrame: CGRect, bgColor aColor: UIColor) {
        bgColor = aColor;

        super.init(frame: aFrame)

        addTarget(self, action: Selector("buttonTouched:"), forControlEvents: .TouchUpInside)
        backgroundColor = aColor;

        setImage(UIImage(named: "flips.png") as UIImage?, forState: .Normal)
    }

    required init(coder aDecoder: NSCoder) {
        bgColor = UIColor.lightGrayColor()
        super.init(coder: aDecoder)
    }

    func buttonTouched(sender: UIButton) {
        if backgroundColor == UIColor.lightGrayColor() {
            backgroundColor = bgColor
        } else {
            backgroundColor = UIColor.lightGrayColor()
        }
    }
}

另外,值得一提的是图像flips.png在我的images.xassets文件夹中,如果这有所不同.

Answer 1

你忘了这个buttonType属性.此外,你最好不要子类UIButton(看看这个为理由).

相反,您应该在启动按钮时将buttonType属性设置为UIButtonTypeCustom一些示例代码:

var myButton = UIButton.buttonWithType(.UIButtonTypeCustom)
myButton.setImage(UIImage(named: "flips.png") as UIImage?, forState: .Normal)

myButton.addTarget(self, action: Selector("buttonTouched:"), forControlEvents: .TouchUpInside)

func buttonTouched(sender: UIButton) {
    if sender.backgroundColor == UIColor.lightGrayColor() {
        sender.backgroundColor = bgColor
    } else {
        sender.backgroundColor = UIColor.lightGrayColor()
    }
}

- 编辑 -

如果你想重用风格的配置,更好的方法是定义你自己的工厂方法的UIButton.就像是:

import Foundation
import UIKit
import ObjectiveC

private var bgColorKey: UInt8 = 0

extension UIButton {

    var bgColor: UIColor {
        get {
            return objc_getAssociatedObject(self, &bgColorKey) as! UIColor
        }
        set (neewColor) {
            objc_setAssociatedObject(self, &bgColorKey, neewColor, .OBJC_ASSOCIATION_RETAIN)
        }
    }

    class func buttonWithFrame(f: CGRect, backgroundColor color: UIColor) -> UIButton {
        let button = UIButton(type: .Custom)
        button.frame = f
        button.backgroundColor = color;
        button.bgColor = color
        button.setImage(UIImage(named: "flips.png") as UIImage?, forState: .Normal)
        button.addTarget(button, action: "buttonTouched:", forControlEvents: .TouchUpInside)
        return button
    }

    func buttonTouched(sender: UIButton) {
        if sender.backgroundColor == UIColor.lightGrayColor() {
            sender.backgroundColor = sender.bgColor
        } else {
            sender.backgroundColor = UIColor.lightGrayColor()
        }
    }
}

然后你可以使用如下按钮:

var btn = UIButton.buttonWithFrame(CGRectMake(50, 50, 100, 50), backgroundColor: UIColor.greenColor())
self.view.addSubview(btn)