iOS 不规则的ImageView

我们在做iOS开发的时候，往往需要实现不规则形状的头像，如：

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

声明了用于maskLayer个CAShapedLayer， CAShapedLayer有个path的属性，将内容Layer的mask设置为maskLayer, 就可以获取到我们想要的形状。

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];

的效果:

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 + 22 *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 + 22 * radius, origin.y, origin.x + 22 * radius, origin.y + radius, radius);
 CGPathAddArcToPoint(path, NULL, origin.x + 22 * radius, origin.y + 22 * radius, origin.x + radius, origin.y + 2  * radius, radius);
 CGPathAddLineToPoint(path, NULL, origin.x, origin.y + 22 * 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];

将是这个效果:

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，那我们

是不是可以通过设置CAShapedLayer的contents来设置maskLayer呢？答案是肯定的，代码如下：

 _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:@"[email protected]"].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:

源代码:https://github.com/heavensword/ShapedImageView