iOS 根据一个View截取图片（含超出一屏的View）

//根据一个View生成一个image

- (UIImage *)screenshotForView:(UIView *)view {

    UIImage *image = nil;

    //判断View类型（一般不是滚动视图或者其子类的话内容不会超过一屏，当然如果超过了也可以通过修改frame来实现绘制）

    if ([view.class isSubclassOfClass:[UIScrollView class]]) {

        UIScrollView *scrView = (UIScrollView *)view;

        CGPoint tempContentOffset = scrView.contentOffset;

        CGRect tempFrame = scrView.frame;

        scrView.contentOffset = CGPointZero;

        scrView.frame = CGRectMake(0, 0, scrView.contentSize.width, scrView.contentSize.height);

        image = [self screenshotForView:scrView size:scrView.frame.size];

        scrView.contentOffset = tempContentOffset;

        scrView.frame = tempFrame;

    } else {

        image = [self screenshotForView:view size:view.frame.size];

    }

    return image;

}

- (UIImage *)screenshotForView:(UIView *)view size:(CGSize)size {

    UIImage *image = nil;

    UIGraphicsBeginImageContextWithOptions(size, YES, [UIScreen mainScreen].scale);

    [view.layer renderInContext:UIGraphicsGetCurrentContext()];

    image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    return image;

}