裁剪图片并保存到相册中

1.加载要裁剪的图片

2.开启一个和图片同样大小的图像上下文（bitmap 图片类型的上下文）

 UIGraphicsBeginImageContextWithOptions(ctxSize, NO, 0.0);

3.获取刚刚开启的图像上下文

 CGContextRef ctx = UIGraphicsGetCurrentContext();

4.建立一个圆形路径

 UIBezierPath * path1 = [UIBezierPath bezierPathWithArcCenter:centerP radius:radius startAngle:0 endAngle:2 * M_PI clockwise:YES];

5.把路径添加到图像上下文中

 CGContextAddPath(ctx, path1.CGPath);

6.执行裁剪

 CGContextClip(ctx);

6.1把图片绘制到图像上下文中

 [image drawAtPoint:CGPointMake(margin, margin)];

7.从图像上下文中获取图片

 UIImage * getImage = UIGraphicsGetImageFromCurrentImageContext();

8.关闭图形上下文

 UIGraphicsEndImageContext();

9.显示图片

self.imageView.image = getImage;

10.保存相册

UIImageWriteToSavedPhotosAlbum(getImage, self, @selector(image:didFinishSavingWithError:contextInfo:), @"hello word");

//写入相册必定实现该方法

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;
{
//     NSLog(@"保存成功 %@",contextInfo);

} 

11.保存到沙盒中

 NSString * docuStr = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    //拼接文件名

NSString * fileName = [docuStr stringByAppendingPathComponent:@"001.png"];

//把图片转化为NSData类型
    NSData * imageData = UIImagePNGRepresentation(getImage);
   

    [imageData writeToFile:fileName atomically:YES];