scrollView截取指定区域的图片

把scrollView放到一个容器里面，再截图就可以了

scrollview放到容器：

    UIView *lunboCarrier = [[UIView alloc] initWithFrame:CGRectMake(, CGRectGetMaxY(self.headerLevelView.frame) + widthWith6(), Main_Screen_Width, widthWith6())];
    [self.headerV addSubview:lunboCarrier];
    lunboCarrier.backgroundColor = [UIColor clearColor];
    _lunboView = [[GXLunBoView alloc] initWithFrame:lunboCarrier.bounds]; // GXLunBoView是轮播图

截图：

+(UIImage*)imageFromView:(UIView *)theView atFrame:(CGRect)rect {

    UIGraphicsBeginImageContext(theView.frame.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSaveGState(context);

    UIRectClip(rect);

    [theView.layer renderInContext:context];

    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return  theImage;

}