2.图片裁剪

1.圆形图片

//图片裁剪
-(UIImage*)image:(UIImage*)image{
    UIGraphicsBeginImageContextWithOptions(image.size, NO, 0);
    CGFloat radius = MIN(image.size.width, image.size.height)*0.5;
    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, radius*2, radius*2)];
    [path addClip];
    [image drawAsPatternInRect:CGRectMake(0, 0, image.size.width, image.size.height)];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

2. 带边框的圆形图片裁剪

-(UIImage*)clipCircleWithBorder:(UIImage*)image{
    //确定边框宽度
    CGFloat borderWidth = 5;
    //确定图片区域大小
    CGFloat width  = MIN(image.size.width, image.size.height);
    //上下文尺寸
    CGSize size = CGSizeMake(width+ borderWidth*2, width+borderWidth*2);
    //开辟一个上下文
    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
    //绘制大圆，显示出来
    UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(0, 0, size.width, size.width)];
    [[UIColor blueColor]set];
    [path fill];
    //绘制小圆，裁剪路径
    UIBezierPath *clipPath = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(borderWidth, borderWidth, width, width)];
    [clipPath addClip];
    [image drawAtPoint:CGPointMake(borderWidth, borderWidth)];
    UIImage *newImage =  UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

3. 截屏

-(UIImage*)clipScreen{
    UIGraphicsBeginImageContextWithOptions(self.view.bounds.size, NO, 0);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [self.view.layer renderInContext:ctx];
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return newImage;
}

//保存图片到沙盒
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    UIImage *image = [self clipScreen];
    NSArray<NSString*> *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString * path = [[paths lastObject]stringByAppendingPathComponent:@"2.png"];
    NSLog(@"%@",path);
    //把图片转成二进制流，可以做图片压缩(0到1)，1表示原始质量，不压缩
    //NSData *data  = UIImageJPEGRepresentation(image, 1);//转成jpg
    NSData *data  = UIImagePNGRepresentation(image);//转成png
    [data writeToFile:path atomically:YES];
}