在項目里,經常會用到圓角的圖片,把寫的分類分享給大家

創建一個UIImage的分類,把代碼粘過去就OK

#import <UIKit/UIKit.h>

@interface UIImage (DY)

(instancetype)circleImageWithName:(NSString )name borderWidth:(CGFloat)borderWidth borderColor:(UIColor )borderColor;

@end

import "UIImage+DY.h"
@implementation UIImage (DY)

(instancetype)circleImageWithName:(NSString )name borderWidth:(CGFloat)borderWidth borderColor:(UIColor )borderColor
{
  // 1.加載原圖
  UIImage *oldImage = [UIImage imageNamed:name];
// 2.開啟上下文
  CGFloat imageW = oldImage.size.width + 2  borderWidth;
  CGFloat imageH = oldImage.size.height + 2  borderWidth;
  CGSize imageSize = CGSizeMake(imageW, imageH);
  UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
// 3.取得當前的上下文
  CGContextRef ctx = UIGraphicsGetCurrentContext();
// 4.畫邊框(大圓)
  [borderColor set];
  CGFloat bigRadius = imageW  0.5; // 大圓半徑
  CGFloat centerX = bigRadius; // 圓心
  CGFloat centerY = bigRadius;
  CGContextAddArc(ctx, centerX, centerY, bigRadius, 0, M_PI  2, 0);
  CGContextFillPath(ctx); // 畫圓
// 5.小圓
  CGFloat smallRadius = bigRadius - borderWidth;
  CGContextAddArc(ctx, centerX, centerY, smallRadius, 0, M_PI * 2, 0);
  // 裁剪(后面畫的東西才會受裁剪的影響)
  CGContextClip(ctx);
// 6.畫圖
  [oldImage drawInRect:CGRectMake(borderWidth, borderWidth, oldImage.size.width, oldImage.size.height)];
// 7.取圖
  UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
// 8.結束上下文
  UIGraphicsEndImageContext();
return newImage;
}


@end</pre>