iOS 不规则的UIImageView 实现

那如何去实现？

通常图片都是矩形的，如果想在客户端去实现不规则的头像，需要自己去实现。

1.使用layer去实现, 见http://blog.csdn.net/johnzhjfly/article/details/39993345

2.使用CAShapeLayer, CALayer如何去实现

我们来看看如何使用CAShapeLayer去实现,

定义一个ShapedImageView，继承于UIView， 代码如下：

#import "ShapedImageView.h"

@interface ShapedImageView()
{
    CALayer      *_contentLayer;
    CAShapeLayer *_maskLayer;
}
@end

@implementation ShapedImageView

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        [self setup];
    }
    return self;
}

- (void)setup
{
    _maskLayer = [CAShapeLayer layer];
    _maskLayer.path = [UIBezierPath bezierPathWithOvalInRect:self.bounds].CGPath;
    _maskLayer.fillColor = [UIColor blackColor].CGColor;
    _maskLayer.strokeColor = [UIColor redColor].CGColor;
    _maskLayer.frame = self.bounds;
    _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1);
    _maskLayer.contentsScale = [UIScreen mainScreen].scale;
    
    _contentLayer = [CALayer layer];
    _contentLayer.mask = _maskLayer;
    _contentLayer.frame = self.bounds;
    [self.layer addSublayer:_contentLayer];
    
}

- (void)setImage:(UIImage *)image
{
    _contentLayer.contents = (id)image.CGImage;
}

@end

path我们可以使用CAMutablePath任意的构造，上述的代码运行想过如下：

如果将代码改成

    _maskLayer = [CAShapeLayer layer];
    _maskLayer.path = [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius:20].CGPath;
    _maskLayer.fillColor = [UIColor blackColor].CGColor;
    _maskLayer.strokeColor = [UIColor redColor].CGColor;
    _maskLayer.frame = self.bounds;
    _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1);
    _maskLayer.contentsScale = [UIScreen mainScreen].scale;                 //非常关键设置自动拉伸的效果且不变形
    
    _contentLayer = [CALayer layer];
    _contentLayer.mask = _maskLayer;
    _contentLayer.frame = self.bounds;
    [self.layer addSublayer:_contentLayer];

如果将代码改成:

    CGMutablePathRef path = CGPathCreateMutable();
    CGPoint origin = self.bounds.origin;
    CGFloat radius = CGRectGetWidth(self.bounds) / 2;
    CGPathMoveToPoint(path, NULL, origin.x, origin.y + 2 *radius);
    CGPathMoveToPoint(path, NULL, origin.x, origin.y + radius);
    
    CGPathAddArcToPoint(path, NULL, origin.x, origin.y, origin.x + radius, origin.y, radius);
    CGPathAddArcToPoint(path, NULL, origin.x + 2 * radius, origin.y, origin.x + 2 * radius, origin.y + radius, radius);
    CGPathAddArcToPoint(path, NULL, origin.x + 2 * radius, origin.y + 2 * radius, origin.x + radius, origin.y + 2  * radius, radius);
    CGPathAddLineToPoint(path, NULL, origin.x, origin.y + 2 * radius);
    
    _maskLayer = [CAShapeLayer layer];
    _maskLayer.path = path;
    _maskLayer.fillColor = [UIColor blackColor].CGColor;
    _maskLayer.strokeColor = [UIColor clearColor].CGColor;
    _maskLayer.frame = self.bounds;
    _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1);
    _maskLayer.contentsScale = [UIScreen mainScreen].scale;                 //非常关键设置自动拉伸的效果且不变形
    
    _contentLayer = [CALayer layer];
    _contentLayer.mask = _maskLayer;
    _contentLayer.frame = self.bounds;
    [self.layer addSublayer:_contentLayer];

理论上我们可以构造出任意想要的形状，但是有些形状如果你不熟悉几何知识的话是构造不出正确的

path的，从代码上我们可以看到我们可以通过设置CALayer的contents属性来设置显示的内容，那我啤"http://www.2cto.com/kf/web/php/" target="_blank" class="keylink">PHPC9wPgo8cD7Kx7K7yse/ydLUzai5/cno1sNDQVNoYXBlZExheWVytcRjb250ZW50c8C0yejWw21hc2tMYXllcsTYo7+08LC4yse/z7aotcSjrLT6wuvI58/Co7o8L3A+CjxwPjwvcD4KPHByZSBjbGFzcz0="brush:java;"> _maskLayer = [CAShapeLayer layer]; _maskLayer.fillColor = [UIColor blackColor].CGColor; _maskLayer.strokeColor = [UIColor clearColor].CGColor; _maskLayer.frame = self.bounds; _maskLayer.contentsCenter = CGRectMake(0.5, 0.5, 0.1, 0.1); _maskLayer.contentsScale = [UIScreen mainScreen].scale; //非常关键设置自动拉伸的效果且不变形 _maskLayer.contents = (id)[UIImage imageNamed:@"gray_bubble_right@2x.png"].CGImage; _contentLayer = [CALayer layer]; _contentLayer.mask = _maskLayer; _contentLayer.frame = self.bounds; [self.layer addSublayer:_contentLayer];

gray_bubble_right就是你想要的形状，运行效果如下: