根据size调整图片背景

比如给 self.view设置背景图片，发现图片小了或者没延伸开来，这时候应该根据size来调整图片了

-(UIImage *)OriginImage:(UIImage *)image scaleToSize:(CGSize)size{
    UIGraphicsBeginImageContext(size);
    [image drawInRect:CGRectMake(0, 0, size.width, size.height)];
    UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return scaledImage;
}
调用这个函数，然后

 UIImage *image = [self OriginImage:self.imageview.image scaleToSize:CGSizeMake(self.view.frame.size.width, self.view.frame.size.height)];
 self.view.backgroundColor = [UIColor colorWithPatternImage:image];