使用Setter和Getter方法与直接操作的好处 [英] Benefits of using Setter and Getter methods vs. direct manipulation

问题描述

对不起，如果这是一个初学者问题，但我想知道什么好处是使用setter和getter方法，而不是直接操作它们。我在obj-c，我想知道是否在内存/ cpu使用方面有任何好处。

Sorry if this a beginner question but I was wondering what the benefits are to using setter and getter methods rather than directly manipulating them directly. I'm in obj-c and I'm wondering if there is any benefits in terms of memory/cpu usage.

例如，我裁剪图像之前我上传它，我裁剪它后，采取/挑。我把所有的代码放在 didFinishPickingMediaWithInfo 方法中。所以它看起来像下面：

For instance, I'm cropping an image before I upload it and I crop it after it is taken/picked. I put all my code in the didFinishPickingMediaWithInfo method. So it would look like the following:

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

    //Create image
    imageFile = [info objectForKey:UIImagePickerControllerOriginalImage];

    //Unhide imageView and populate
    selectedImage.hidden = false;
    selectedImage.image = imageFile;

    //Create original image for reservation
    originalImage = imageFile;

    //Crop image
    UIGraphicsBeginImageContext(selectedImage.frame.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextRotateCTM(context, 2*M_PI);

    [selectedImage.layer renderInContext:context];
    imageFile =  UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //Update imageView with croppedImage
    selectedImage.image = imageFile;

    //Dismiss image picker
    [imagePickerController dismissViewControllerAnimated:YES completion:nil];

}

所以让我们说我做同样的事情，用于填充 selectedImage imageView和用于裁剪图像的方法，如下所示：

So let's say I do the same thing but have a method for populating the selectedImage imageView and a method for cropping the image so it would look like the following:

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info{

    //Create image
    [self setImage:[info objectForKey:UIImagePickerControllerOriginalImage]];

    //Create local image
    UIImage * localImage = [self returnImage];

    //Unhide imageView and populate
    selectedImage.hidden = false;
    [self populateImageView:localImage];

    //Create original image for reservation
    originalImage = localImage;

    //Crop image
    localImage = [self getImageFromContext:localImage withImageView:selectedImage];

    //Update imageView with croppedImage
    [self populateImageView:localImage];

    //Dismiss image picker
    [imagePickerController dismissViewControllerAnimated:YES completion:nil];

}

//Crop image method
-(UIImage *)getImageFromContext:(UIImage *)image withImageView:(UIImageView *)imageView{

    UIGraphicsBeginImageContext(imageView.frame.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextRotateCTM(context, 2*M_PI);

    [imageView.layer renderInContext:context];
    image =  UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;

    image = nil;
    context = nil;

}

-(void)populateImageView:(UIImage *)image{

    selectedImage.image = image;

}

- (void)setImage:(UIImage *)image{

    imageFile = image;

}

-(UIImage *)returnImage{

    return imageFile;

}

除了可读性和整洁性，还有其他好处码？

So are there any other benefits other than readability and neatness of code? Is there anyway to make this more efficient?

推荐答案

您有一个 Big Nerd Ranch制作的伟大基准。

通常我使用属性作为最佳实践。这是有用的，因为您有：

Usually I use properties as a best practice. This is useful because you have:

• 您的资源将被访问的预期地点（getter）

这通常有助于调试（可以覆盖setter或set一个断点，以检查谁正在改变属性，当它正在改变），你可以做一些延迟实例化。

This usually helps in debugging (you can override the setter or set a breakpoint there to check who is changing the property and when it is changing) and you can do some lazy instantiation.

通常我做延迟实例化数组或用程序创建视图。例如：

Usually I do lazy instantiation with arrays or with programmatically created views. For instance:

@property(nonatomic, strong) UIView *myView;

-(UIView*) myView {
   if(!_myView) {
       //I usually prefer a function over macros
       _myView = [[UIView alloc] initWithFrame: [self myViewFrame]];
       _myView.backgroundColor = [UIColor redColor];
   }

   return _myView;
}

另一个重要的因素以 Jacky Boy 是属性，你有一个免费的KVO ready结构。

Another important factor bolded by Jacky Boy is that with properties you have a free KVO ready structure.

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