iOS 屏幕截图

/**
 
 *截图功能
 
 */

+(UIImage *)screenShotFromView:(UIView *)view area:(CGRect)rect dstSize:(CGSize)dsize {
    
    UIGraphicsBeginImageContextWithOptions(dsize, YES, 0);
    
    [[view layer] renderInContext:UIGraphicsGetCurrentContext()];
    
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    
    UIGraphicsEndImageContext();
    
    CGImageRef imageRef = viewImage.CGImage;
    
    CGImageRef imageRefRect =CGImageCreateWithImageInRect(imageRef, rect);
    
    UIImage *sendImage = [[UIImage alloc] initWithCGImage:imageRefRect];
    
    NSData *imageViewData = UIImagePNGRepresentation(sendImage);
    
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    
    NSString *documentsDirectory = [paths objectAtIndex:0];
    
    NSString *pictureName= @"screenShow.png";
    
    NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:pictureName];
    
    //保存照片到沙盒目录
    [imageViewData writeToFile:savedImagePath atomically:YES];
    
    CGImageRelease(imageRefRect);
    
    //从手机本地加载图片
    
    UIImage *bgImage2 = [[UIImage alloc]initWithContentsOfFile:savedImagePath];
    
    return bgImage2;
}


- (void)screenShotFromScrollView:(UIScrollView *)view area:(CGRect)rect dstSize:(CGSize)dsize {
    
    UIImage* image = nil;
    
    UIGraphicsBeginImageContext(view.contentSize);
    
    {
        
        CGPoint savedContentOffset = view.contentOffset;
        
        CGRect savedFrame = view.frame;
        
        view.contentOffset = CGPointZero;
        
        view.frame = CGRectMake(0, 0, view.contentSize.width, view.contentSize.height);       [view.layer renderInContext: UIGraphicsGetCurrentContext()];
        
        image = UIGraphicsGetImageFromCurrentImageContext();
        
        view.contentOffset = savedContentOffset;
        
        view.frame = savedFrame;
        
    }
    
    UIGraphicsEndImageContext();
    
    if (image != nil) {
        
        NSLog(@"截图成功!");
        
    }
    
}

出现这个错，一般是因为 frame中的高或宽为0或负值。

 <Error>: CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.