Quartz2D 制作圆形图片(头像)

//1.加载原图
UIImage *oldImage = [UIImage imageNamed:@"girl"];

//2.开启上下文
UIGraphicsBeginImageContextWithOptions(oldImage.size, NO, 0.0);

//3.取得当前的上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();

//4.画圆
CGRect circleRect = CGRectMake(0, 0, oldImage.size.width, oldImage.size.height);
CGContextAddEllipseInRect(ctx, circleRect);

//5.裁剪(按照当前的路径形状裁剪)
CGContextClip(ctx);

//6.画图
[oldImage drawInRect:circleRect];

//7.取图
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

//8.结束
UIGraphicsEndImageContext();

//9.写出文件
NSData *data = UIImagePNGRepresentation(newImage);
NSString *path = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
NSString *realpath = [path stringByAppendingPathComponent:@"new.png"];
[data writeToFile:realpath atomically:YES];
//打印一下图片的沙盒路径
NSLog(@"%@",realpath);