ZYCornerRadius - 一句代码，圆角风雨无阻

A Category to make cornerRadius for UIImageView have no Offscreen-Rendered, be more efficiency
避免为UIImageView设置圆角时触发离屏渲染所带来的性能损耗，两种工作方式：Category和UIImageView子类。

##CocoaPods: ``` pod 'ZYCornerRadius', '~> 0.6.1' ```
##性能对比: 测试设备6P，屏幕中有40张尺寸为20*20的小图片，使用masksToBounds切角处理时帧率大大下降至20+，使用ZYCornerRadius时帧率保持在57+，性能接近0损耗。 
##Usage: >ZYCornerRadius提供两种使用方式

Category方式：
导入头文件

#import "UIImageView+CornerRadius.h"

创建圆角半径为6的UIImageView(三种方式)：

//1
UIImageView *imageView = [UIImageView zy_cornerRadiusAdvance:6.0f rectCornerType:UIRectCornerAllCorners];
imageView.image = [UIImage imageNamed:@"mac_dog"];

//2
UIImageView *imageView = [[UIImageView alloc] initWithCornerRadiusAdvance:6.0f rectCornerType:UIRectCornerAllCorners];
imageView.image = [UIImage imageNamed:@"mac_dog"];

//3
UIImageView *imageView = [[UIImageView alloc] init];
[imageView zy_cornerRadiusAdvance:6.0f rectCornerType:UIRectCornerAllCorners];
imageView.image = [UIImage imageNamed:@"mac_dog"];

创建圆形的UIImageView(三种方式)：

//1
UIImageView *imageView = [UIImageView zy_roundingRectImageView];
imageView.image = [UIImage imageNamed:@"mac_dog"];

//2
UIImageView *imageView = [[UIImageView alloc] initWithRoundingRectImageView];
imageView.image = [UIImage imageNamed:@"mac_dog"];

//3
UIImageView *imageView = [[UIImageView alloc] init];
[imageView zy_cornerRadiusRoundingRect];
imageView.image = [UIImage imageNamed:@"mac_dog"];

子类ZYImageView方式同理：
导入头文件

#import "ZYImageView.h"

使用方式同理

##以下列出ZYCornerRadius所开放的主要的func: 配置一个圆角UIImageView，传入圆角半径和圆角类型 ```objc + (UIImageView *)zy_cornerRadiusAdvance:(CGFloat)cornerRadius rectCornerType:(UIRectCorner)rectCornerType; - (instancetype)initWithCornerRadiusAdvance:(CGFloat)cornerRadius rectCornerType:(UIRectCorner)rectCornerType; ``` 配置一个圆形的UIImageView ```objc + (UIImageView *)zy_roundingRectImageView; - (instancetype)initWithRoundingRectImageView; ``` 直接为UIImageView设置圆角图片，传入UIImage，圆角半径和圆角类型，当次有效 ```objc - (void)zy_cornerRadiusWithImage:(UIImage *)image cornerRadius:(CGFloat)cornerRadius rectCornerType:(UIRectCorner)rectCornerType; ```
##iteration: 0.6.1 - 解决在TableViewCell被selected后，其中UIImageView的image被重置的问题 0.5.1 - 解决SDWebImage使用placeholder为nil时发生的crash 0.4.1 - 发布第一个较完善版本
##Relation: [@liuzhiyi1992](https://github.com/liuzhiyi1992) on Github [@Blog](http://zyden.vicp.cc/) Welcome
##License: ZYCornerRadius is released under the MIT license. See LICENSE for details.