1:首先将一张图片裁剪成圆形图片,,

/**圆形图片裁剪*/- (UIImage *)wjf_circleImage {    //利用self生成一张圆形图片    // 1.开启图形上下文    UIGraphicsBeginImageContextWithOptions(self.size,NO,0);    // 2.描述圆形路径    UIBezierPath*path = [UIBezierPathbezierPathWithOvalInRect:CGRectMake(0,0,    self.size.width,self.size.height)];    // 3.设置裁剪区域    [pathaddClip];    // 4.画图    [selfdrawAtPoint:CGPointZero];    // 5.取出图片    UIImage*image =UIGraphicsGetImageFromCurrentImageContext();    // 6.关闭上下文    UIGraphicsEndImageContext();    returnimage;}

2:用CGContextClearRect 的功能 制作环形图片

- (UIImage*)getClearRectImage:(UIImage*)image{    UIGraphicsBeginImageContextWithOptions(image.size,NO,0.0f);    CGContextRefctx =UIGraphicsGetCurrentContext();    //默认绘制的内容尺寸和图片一样大,从某一点开始绘制    [imagedrawAtPoint:CGPointZero];    CGFloatbigRaduis = image.size.width/5;    CGRectcirleRect =CGRectMake(image.size.width/2-bigRaduis,     image.size.height/2-bigRaduis, bigRaduis*2, bigRaduis*2);    //CGContextAddArc(ctx,image.size.width/2-bigRaduis,image.size.height/2-bigRaduis,     bigRaduis, 0.0, 2*M_PI, 0);    CGContextAddEllipseInRect(ctx,cirleRect);    CGContextClip(ctx);    CGContextClearRect(ctx,cirleRect);    UIImage*newImage =UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    returnnewImage;}

如果你的图片是正方形的话,就大功告成了,但是你的图片是长方形呢，不用怕.

注:将长方形图片变成正方形图片:

- (UIImage * ) getSquareImage: (UIImage *) image RangeCGRect: (CGRect) range centerBool: (BOOL) centerBool {    /*如若centerBool为Yes则是由中心点取mCGRect范围的图片*/    floatimgWidth = image.size.width;    floatimgHeight = image.size.height;    floatviewWidth = range.size.width;    floatviewHidth = range.size.height;    CGRectrect;    if (centerBool)    rect = CGRectMake((imgWidth - viewWidth) / 2,    (imgHeight - viewHidth) / 2, viewWidth, viewHidth);    else {        if (viewHidth        {            if (imgWidth <= imgHeight) {                rect = CGRectMake(0, 0, imgWidth, imgWidth * viewHidth / viewWidth);            } else {                floatwidth = viewWidth * imgHeight / viewHidth;                floatx = (imgWidth - width) / 2;                if (x > 0) {                    rect = CGRectMake(x, 0, width, imgHeight);                } else {                    rect = CGRectMake(0, 0, imgWidth, imgWidth * viewHidth / viewWidth);                }            }        } else {            if (imgWidth <= imgHeight) {                floatheight = viewHidth * imgWidth / viewWidth;                if (height < imgHeight) {                    rect = CGRectMake(0, 0, imgWidth, height);                } else                {                    rect = CGRectMake(0, 0, viewWidth * imgHeight / viewHidth, imgHeight);                }            } else            {                floatwidth = viewWidth * imgHeight / viewHidth;                if (width < imgWidth)                {                    floatx = (imgWidth - width) / 2;                    rect = CGRectMake(x, 0, width, imgHeight);                } else                {                    rect = CGRectMake(0, 0, imgWidth, imgHeight);                }            }        }    }    CGImageRefSquareImageRef = CGImageCreateWithImageInRect(image.CGImage, rect);    CGRectSquareImageBounds = CGRectMake(0, 0, CGImageGetWidth(SquareImageRef),     CGImageGetHeight(SquareImageRef));    UIGraphicsBeginImageContext(SquareImageBounds.size);    CGContextRefcontext = UIGraphicsGetCurrentContext();    CGContextDrawImage(context, SquareImageBounds, SquareImageRef);    UIImage * SquareImage = [UIImageimageWithCGImage: SquareImageRef];    UIGraphicsEndImageContext();    returnSquareImage;}

当然这是就用到了UIimage的size的属性了.

CGSize size = yuanlai.size;float imageSize;NSLog(@"size==height%f====width%f",size.height,size.width);if(size.height>= size.width) {    imageSize = size.width;}else{    imageSize = size.height;}

裁剪出环形图片