利用UIBezierPath這個(gè)類畫(huà)出圓形圖片

- (UIImage*)drawImageWithSize:(CGSize)size imageName:(NSString *)imageName

{

    // 申請(qǐng)一塊特定大小的畫(huà)布

    UIGraphicsBeginImageContext(size);

    // 畫(huà)出一個(gè)與畫(huà)布等大的圓

    UIBezierPath *path = [UIBezierPathbezierPathWithOvalInRect:CGRectMake(0,0, size.width, size.height)];

    // 將這個(gè)圓以外的部分設(shè)置為無(wú)效區(qū)

    [path addClip];

    UIImage *oldImage = [UIImageimageNamed:imageName];

    [oldImage drawInRect:CGRectMake(0,0, size.width, size.height)];

    UIImage *newImage =UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return newImage;

}

imageView.image =newImage;