iOS截图

-(void)saveHistory{    UIImage *image = [self captureImageFromView:self.view];    ALAssetsLibrary  *library = [ALAssetsLibrary new];    NSData *date = UIImageJPEGRepresentation(image, 1.0);    [library writeImageDataToSavedPhotosAlbum:date metadata:nil completionBlock:nil];}-(UIImage *)captureImageFromView:(UIView *)view{    CGRect screenRect = [view bounds];    UIGraphicsBeginImageContext(screenRect.size);    CGContextRef ref = UIGraphicsGetCurrentContext();    [view.layer renderInContext:ref];    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();    UIGraphicsEndImageContext();    return image;}