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如何在UIButton子类中重写-drawrect?

iphoneuibutton
12

你好。我需要在自定义按钮上写一些文本，所以我子类化了UIButton。在-drawrect中，我编写了所需的文本。问题是文本最终会出现在按钮下方。在我编写文本后，UIButton的drawrect会在我的上方绘制。

即使我之前打算在进行绘制之前调用[super drawrect：rect]，但我甚至没有调用它。似乎无论如何都会调用UIButton的drawrect。

有什么想法吗？谢谢。

5个回答
20

如其他人所说，你无需子类化UIButton - 事实上最好不要这样做，因为UIButton很复杂（正如你发现的那样）。你有三个选择：

  • 将按钮的标题留空，在你想要的位置上添加一个新的文本框。
  • 如果你正在使用3.0，则访问按钮的标签属性。虽然标签本身是只读的，但它的属性（包括框架）不是。
  • 子类化UIControl。UIControl是一个UIView，所以你可以添加其他视图 - 文本和图像，并且它是UIView实现操作消息行为（addTarget:action:forControlEvents:）。UIButton在其上实现了状态性。

如果你不需要像UIButton的setTitle:forState:和相关功能之类的东西，但你正在使用很多这些控件，我会使用第三个选项。否则使用第一个选项（如果你在3.0上使用第二个选项）。

5

这对我来说很有效（忽略复杂的绘图代码）。

  1. 创建一个UIButton的子类
  2. 在StoryBoard中创建一个UIButton
  3. 进入Identity Inspector，输入您自定义按钮类的名称

这是我的UIButton代码：

h文件：

#import <UIKit/UIKit.h>

@interface DoneButton : UIButton

@property (assign, nonatomic) BOOL selected;

@end

m文件：

 #import "DoneButton.h"

    @implementation DoneButton

    @synthesize selected = _selected;

    - (id)initWithFrame:(CGRect)frame
    {
        self = [super initWithFrame:frame];
        if (self) {
            // Initialization code
        }
        return self;
    }

    - (void)setSelected:(BOOL)selected
    {
        if (_selected != selected) {
            _selected = selected;
            [self setNeedsDisplay];
        }
    }


    - (void)drawRect:(CGRect)rect
    {
        // Drawing code

        if (_selected) {
            //// Color Declarations
            UIColor* color2 = [UIColor colorWithRed: 0 green: 0 blue: 0 alpha: 1];

            //// Bezier Drawing
            UIBezierPath* bezierPath = [UIBezierPath bezierPath];
            [bezierPath moveToPoint: CGPointMake(49.39, 31.25)];
            [bezierPath addLineToPoint: CGPointMake(49.39, 31.25)];
            [bezierPath addCurveToPoint: CGPointMake(46.64, 25.19) controlPoint1: CGPointMake(49.39, 29.02) controlPoint2: CGPointMake(48.38, 26.94)];
            [bezierPath addCurveToPoint: CGPointMake(44.3, 18.95) controlPoint1: CGPointMake(46.63, 22.72) controlPoint2: CGPointMake(45.88, 20.53)];
            [bezierPath addCurveToPoint: CGPointMake(42.44, 17.59) controlPoint1: CGPointMake(43.75, 18.4) controlPoint2: CGPointMake(43.13, 17.95)];
            [bezierPath addCurveToPoint: CGPointMake(38.07, 16.61) controlPoint1: CGPointMake(41.17, 16.93) controlPoint2: CGPointMake(39.67, 16.62)];
            [bezierPath addCurveToPoint: CGPointMake(33.15, 13.95) controlPoint1: CGPointMake(36.62, 15.18) controlPoint2: CGPointMake(34.95, 14.23)];
            [bezierPath addCurveToPoint: CGPointMake(32.78, 13.92) controlPoint1: CGPointMake(33.03, 13.93) controlPoint2: CGPointMake(32.9, 13.93)];
            [bezierPath addCurveToPoint: CGPointMake(32, 13.86) controlPoint1: CGPointMake(32.52, 13.89) controlPoint2: CGPointMake(32.26, 13.86)];
            [bezierPath addLineToPoint: CGPointMake(32, 13.86)];
            [bezierPath addLineToPoint: CGPointMake(32, 13.86)];
            [bezierPath addLineToPoint: CGPointMake(32, 13.86)];
            [bezierPath addLineToPoint: CGPointMake(32, 13.86)];
            [bezierPath addCurveToPoint: CGPointMake(31.38, 13.91) controlPoint1: CGPointMake(31.79, 13.86) controlPoint2: CGPointMake(31.59, 13.89)];
            [bezierPath addCurveToPoint: CGPointMake(30.85, 13.95) controlPoint1: CGPointMake(31.2, 13.92) controlPoint2: CGPointMake(31.02, 13.92)];
            [bezierPath addCurveToPoint: CGPointMake(26.92, 15.74) controlPoint1: CGPointMake(29.44, 14.17) controlPoint2: CGPointMake(28.12, 14.8)];
            [bezierPath addCurveToPoint: CGPointMake(25.94, 16.61) controlPoint1: CGPointMake(26.58, 16.01) controlPoint2: CGPointMake(26.25, 16.29)];
            [bezierPath addCurveToPoint: CGPointMake(24.13, 16.76) controlPoint1: CGPointMake(25.31, 16.61) controlPoint2: CGPointMake(24.71, 16.66)];
            [bezierPath addCurveToPoint: CGPointMake(19.7, 18.95) controlPoint1: CGPointMake(22.41, 17.06) controlPoint2: CGPointMake(20.88, 17.77)];
            [bezierPath addCurveToPoint: CGPointMake(17.36, 25.19) controlPoint1: CGPointMake(18.12, 20.53) controlPoint2: CGPointMake(17.37, 22.72)];
            [bezierPath addCurveToPoint: CGPointMake(14.61, 31.25) controlPoint1: CGPointMake(15.62, 26.94) controlPoint2: CGPointMake(14.61, 29.02)];
            [bezierPath addLineToPoint: CGPointMake(14.61, 31.25)];
            [bezierPath addCurveToPoint: CGPointMake(14.61, 31.25) controlPoint1: CGPointMake(14.61, 31.25) controlPoint2: CGPointMake(14.61, 31.25)];
            [bezierPath addCurveToPoint: CGPointMake(14.66, 31.92) controlPoint1: CGPointMake(14.61, 31.48) controlPoint2: CGPointMake(14.64, 31.7)];
            [bezierPath addCurveToPoint: CGPointMake(14.7, 32.4) controlPoint1: CGPointMake(14.67, 32.08) controlPoint2: CGPointMake(14.67, 32.24)];
            [bezierPath addCurveToPoint: CGPointMake(15.86, 35.44) controlPoint1: CGPointMake(14.86, 33.46) controlPoint2: CGPointMake(15.27, 34.48)];
            [bezierPath addCurveToPoint: CGPointMake(15.97, 35.64) controlPoint1: CGPointMake(15.9, 35.5) controlPoint2: CGPointMake(15.93, 35.57)];
            [bezierPath addCurveToPoint: CGPointMake(17.36, 37.32) controlPoint1: CGPointMake(16.36, 36.23) controlPoint2: CGPointMake(16.83, 36.78)];
            [bezierPath addCurveToPoint: CGPointMake(17.49, 38.98) controlPoint1: CGPointMake(17.36, 37.89) controlPoint2: CGPointMake(17.41, 38.44)];
            [bezierPath addCurveToPoint: CGPointMake(18.35, 41.7) controlPoint1: CGPointMake(17.65, 39.95) controlPoint2: CGPointMake(17.92, 40.87)];
            [bezierPath addCurveToPoint: CGPointMake(19.7, 43.55) controlPoint1: CGPointMake(18.7, 42.38) controlPoint2: CGPointMake(19.15, 43)];
            [bezierPath addCurveToPoint: CGPointMake(25.93, 45.89) controlPoint1: CGPointMake(21.28, 45.13) controlPoint2: CGPointMake(23.47, 45.88)];
            [bezierPath addCurveToPoint: CGPointMake(27.61, 47.28) controlPoint1: CGPointMake(26.47, 46.42) controlPoint2: CGPointMake(27.02, 46.89)];
            [bezierPath addCurveToPoint: CGPointMake(32, 48.64) controlPoint1: CGPointMake(28.96, 48.16) controlPoint2: CGPointMake(30.44, 48.64)];
            [bezierPath addLineToPoint: CGPointMake(32, 48.64)];
            [bezierPath addLineToPoint: CGPointMake(32, 48.64)];
            [bezierPath addLineToPoint: CGPointMake(32, 48.64)];
            [bezierPath addLineToPoint: CGPointMake(32, 48.64)];
            [bezierPath addCurveToPoint: CGPointMake(38.06, 45.89) controlPoint1: CGPointMake(34.23, 48.64) controlPoint2: CGPointMake(36.31, 47.63)];
            [bezierPath addCurveToPoint: CGPointMake(44.3, 43.55) controlPoint1: CGPointMake(40.53, 45.88) controlPoint2: CGPointMake(42.72, 45.13)];
            [bezierPath addLineToPoint: CGPointMake(44.3, 43.55)];
            [bezierPath addLineToPoint: CGPointMake(44.3, 43.55)];
            [bezierPath addCurveToPoint: CGPointMake(46.64, 37.31) controlPoint1: CGPointMake(45.88, 41.97) controlPoint2: CGPointMake(46.63, 39.78)];
            [bezierPath addCurveToPoint: CGPointMake(49.39, 31.25) controlPoint1: CGPointMake(48.38, 35.56) controlPoint2: CGPointMake(49.39, 33.48)];
            [bezierPath addLineToPoint: CGPointMake(49.39, 31.25)];
            [bezierPath closePath];
            [color2 setStroke];
            bezierPath.lineWidth = 1;
            [bezierPath stroke];


            //// Bezier 2 Drawing
            UIBezierPath* bezier2Path = [UIBezierPath bezierPath];
            [bezier2Path moveToPoint: CGPointMake(22.42, 29.85)];
            [bezier2Path addLineToPoint: CGPointMake(29.74, 37.17)];
            [bezier2Path addLineToPoint: CGPointMake(41.58, 25.33)];
            bezier2Path.usesEvenOddFillRule = YES;

            [color2 setStroke];
            bezier2Path.lineWidth = 1;
            [bezier2Path stroke];

        } else {

            //// Color Declarations
            UIColor* color3 = [UIColor colorWithRed: 0.5 green: 0.5 blue: 0.5 alpha: 1];

            //// Bezier 2 Drawing
            UIBezierPath* bezier2Path = [UIBezierPath bezierPath];
            [bezier2Path moveToPoint: CGPointMake(22.42, 29.85)];
            [bezier2Path addLineToPoint: CGPointMake(29.74, 37.17)];
            [bezier2Path addLineToPoint: CGPointMake(41.58, 25.33)];
            bezier2Path.usesEvenOddFillRule = YES;

            [color3 setStroke];
            bezier2Path.lineWidth = 1;
            [bezier2Path stroke];
        }
    }

如果按钮被选择，绘制第一段代码；否则，绘制另一段代码。我更喜欢使用Paint Code这种方法，因为可以节省大量时间，并且不需要创建数千个PNG或JPEG文件。

3
根据您在其他答案中的评论，这是一个问“如何使用Y来完成Z”的问题，而实际上您应该问“如何完成Z”。

如果您想要一个按钮在图像上方绘制文本而不是旁边，请将图像设置为按钮的背景图像。请使用setBackgroundImage:forState:而不是setImage:forState:，然后正常设置标题。

无论如何，您都必须在drawRect:中绘制图像，或将文本移动到子视图中以便在图像上方绘制。我提到的解决方案是第二个选项的版本。

有趣的是，当我这样做时，我仍然会在图像下面，现在它是背景图像 - 现在没有前景图像了。我相信正在发生的是我的drawRect被调用，然后调用超级的drawRect，覆盖了我绘制的文本。 - mahboudz
如果您正在使用背景图像，请根本不要使用drawRect：。 背景图像将在drawRect：上方绘制，但您实际上不需要自定义绘图，因为标题将在背景图像上方绘制。 - Becca Royal-Gordon
1
如Brent所说，如果你只需要在图像上添加文本，就不应该覆盖-drawRect:方法。使用setTitle:forState:来设置文本。你的情况听起来正是UIButton设计的初衷-为什么要重新发明轮子呢？ - Nick Forge
2
您不需要为了添加文本而子类化UIButton。以下是在UIViewController子类的-viewDidLoad方法中设置自定义按钮的按钮标题的示例：
UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
button.frame = CGRectMake(0, 0, 44, 44);
[button setTitle:@"x" forState:UIControlStateNormal];
[self.view addSubview:button];

您还可以设置按钮的字体属性或使用-setTitleColor:forState:更改颜色。

让我补充一些细节。该按钮是一个小圆形物体的图像。如果我让默认的标题显示方式发生，标题会出现在按钮的右侧，而不是顶部。因此，我保持标题为空，并希望将标题绘制在按钮之上。在所需的字体大小下，大约可以容纳三个字符。但是，如果我按照上述示例进行操作，"x"将会显示在按钮的旁边，而不是在顶部。 - mahboudz
这是使用setTitle的效果：http://www.flickr.com/photos/glasscyclops/3495881450/ - mahboudz
0
怎么样在按钮的视图上添加一个子视图？这样你就可以完全控制它，不用关心按钮的操作。你甚至可以将其设置为标签并省去drawRect的步骤。
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