Benefits of using Setter and Getter methods vs. direct manipulation - ios

Question

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

Answer 1

You have a great benchmark made by Big Nerd Ranch on that topic.
Usually I use properties as a best practice. This is useful because you have:
An expected place where your property will be accessed (getter)
An expected place where your property will be set (setter)
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.
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;
}
Another important factor bolded by Jacky Boy is that with properties you have a free KVO ready structure.