其中有一个不太规则的label：
这个label顶部的两个角是圆角，底部的两个角是直角，底部还有一个小三角。
思路
CAShapeLayer联合UIBezierPath画一个不规则的layer作为label.layer的mask。
具体实现
1.自定义一个继承自UILabel的IrregularLabel
import "IrregularLabel.h"
@interface IrregularLabel ()
/** 遮罩 */
@property (nonatomic, strong) CAShapeLayer *maskLayer;
/** 路径 */
@property (nonatomic, strong) UIBezierPath *borderPath;
@end
2.在初始化方法中进行相应初始化和设置
(instancetype)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
}
return self;
}
3.在layoutSubviews方法中进行路径的设置
(void)layoutSubviews {
[super layoutSubviews];
// 遮罩层frame
self.maskLayer.frame = self.bounds;
// 设置path起点
[self.borderPath moveToPoint:CGPointMake(0, 10)];
// 左上角的圆角
[self.borderPath addQuadCurveToPoint:CGPointMake(10, 0) controlPoint:CGPointMake(0, 0)];
// 直线，到右上角
[self.borderPath addLineToPoint:CGPointMake(self.bounds.size.width - 10, 0)];
// 右上角的圆角
[self.borderPath addQuadCurveToPoint:CGPointMake(self.bounds.size.width, 10) controlPoint:CGPointMake(self.bounds.size.width, 0)];
// 直线，到右下角
[self.borderPath addLineToPoint:CGPointMake(self.bounds.size.width, self.bounds.size.height)];
// 底部的小三角形
[self.borderPath addLineToPoint:CGPointMake(self.bounds.size.width/2+5, self.bounds.size.height)];
[self.borderPath addLineToPoint:CGPointMake(self.bounds.size.width/2, self.bounds.size.height-5)];
[self.borderPath addLineToPoint:CGPointMake(self.bounds.size.width/2 - 5, self.bounds.size.height)];
// 直线，到左下角
[self.borderPath addLineToPoint:CGPointMake(0, self.bounds.size.height)];
// 直线，回到起点
[self.borderPath addLineToPoint:CGPointMake(0, 10)];
// 将这个path赋值给maskLayer的path
self.maskLayer.path = self.borderPath.CGPath;
}
左上角的坐标是(0,0)
右下角的坐标是(maxX,maxY)
圆角是用的二次贝塞尔曲线，关于二次贝塞尔曲线，我在网上看到一张比较形象的图：
最终效果
(void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.label = [[IrregularLabel alloc] initWithFrame:CGRectMake(90, 200, 200, 40)];
[self.view addSubview:self.label];
self.label.text = @"这是一个不规则label";
self.label.textAlignment = NSTextAlignmentCenter;
self.label.backgroundColor = [UIColor redColor];
self.label.textColor = [UIColor whiteColor];
self.label.font = [UIFont boldSystemFontOfSize:16];
}
效果图：
demo