Swift UIButton子类未显示在设备或模拟器上

Question

I have the following code and have declared IBDesignable.

The DrawRect is shown perfectly well in Interface Builder, but not at all in the Simulator or on Device.

Does anybody have any ideas why?

import UIKit
import QuartzCore

@IBDesignable class VideoButton: UIButton {
    // Only override drawRect: if you perform custom drawing.
    // An empty implementation adversely affects performance during animation.
    override func drawRect(rect: CGRect)
    {

        let color2 = UIColor(red: 0.500, green: 0.500, blue: 0.500, alpha: 0.000)

        //// Oval Drawing
        var ovalPath = UIBezierPath(ovalInRect: CGRectMake(frame.minX + floor(frame.width * 0.03571) + 0.5, frame.minY + floor(frame.height * 0.03571) + 0.5, floor(frame.width * 0.96429) - floor(frame.width * 0.03571), floor(frame.height * 0.96429) - floor(frame.height * 0.03571)))
        color2.setFill()
        ovalPath.fill()
        UIColor.whiteColor().setStroke()
        ovalPath.lineWidth = 3
        ovalPath.stroke()


        //// Rectangle Drawing
        let rectanglePath = UIBezierPath(roundedRect: CGRectMake(frame.minX + floor(frame.width * 0.25714 + 0.5), frame.minY + floor(frame.height * 0.34286 + 0.5), floor(frame.width * 0.60000 + 0.5) - floor(frame.width * 0.25714 + 0.5), floor(frame.height * 0.64286 + 0.5) - floor(frame.height * 0.34286 + 0.5)), cornerRadius: 2)
        color2.setFill()
        rectanglePath.fill()
        UIColor.whiteColor().setStroke()
        rectanglePath.lineWidth = 3
        rectanglePath.stroke()


        //// Bezier Drawing
        var bezierPath = UIBezierPath()
        bezierPath.moveToPoint(CGPointMake(frame.minX + 0.61429 * frame.width, frame.minY + 0.50536 * frame.height))
        bezierPath.addLineToPoint(CGPointMake(frame.minX + 0.75714 * frame.width, frame.minY + 0.34286 * frame.height))
        bezierPath.addLineToPoint(CGPointMake(frame.minX + 0.75714 * frame.width, frame.minY + 0.64286 * frame.height))
        bezierPath.addLineToPoint(CGPointMake(frame.minX + 0.61429 * frame.width, frame.minY + 0.50536 * frame.height))
        bezierPath.closePath()
        bezierPath.lineJoinStyle = kCGLineJoinRound;

        color2.setFill()
        bezierPath.fill()
        UIColor.whiteColor().setStroke()
        bezierPath.lineWidth = 3
        bezierPath.stroke()
        //  }

    }

}

Answer 1

将对“框架”的引用更改为“矩形”，它应该插入设备和模拟器中。

Answer 2

You should not be overriding drawRect: for a UIButton subclass. There is no need; you can customize the look of a UIButton using its various properties and methods. It is far from clear why you are doing this. (The fact that you are doing it, and not calling super , probably explains the problem; but the solution is not, call super , but rather, don't do it in the first place.)

Answer 3

I have been trying to do a similar thing recently - create a subclass of UIButton, overriding drawRect() in order to draw a simple custom icon (I am making a play/stop button that alternates between "Play" and "Stop" on each tap):

Maybe I don't know enough about iOS development yet, but in response to other answers and older posts online that discourage extending the UIButton class, I don't understand why this would be a bad idea. Of course you could customize a button by setting custom background images, but in my opinion this isn't as flexible as overriding drawRect (not to mention it can be a pain to edit your button anytime you want to change something because you have to edit an actual image instead of a few lines of code).

I'm sure there are other ways to achieve the same result (implement a button via a custom UIView listening for touch events, for example), but I think the cleanest and easiest way is still just to extend the UIButton class. After all, it is a subclass itself of UIView .

Regarding your code - it appears to work correctly in my environment, although I had to change the colors slightly to get it to show up against a white background (ie UIColor.blackColor().setStroke() instead of UIColor.whiteColor().setStroke() ). Also, as @Astrodan mentioned, it might be a good idea to use rect instead of frame , since it is being passed to you (although the code worked with frame for me):

Live-rendered Storyboard in XCode:

On iPhone 6 Simulator: