如何把大尺寸UIImage图片作为tabBarController中tabBar icons？

如何把大尺寸图片作为tabBarController中tabBar icons？
以下方法代码可实现。

UIImage *image = [UIImage imageNamed:@”Sample_Image.png”];
self.tabBarItem.image = [self imageWithImage:image scaledToSize:CGSizeMake(30, 30)];

– (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize {
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0.0);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}