Objective C自定义类方法未被调用

Question

So I have this custom class with just a test method that does nslog. I am going to reuse this method many times in my app. The interface looks like this.

@interface TestViewController: UIViewController {  CMImageMover * imageMover }

Then in the view did load I:

imageMover = [[CmImageMover alloc] init];

If I do:

[imageMover testMethod];

Right after the alloc and init it works in the viewDidLoad function but if I call it again from another function in the view controller nothing works and the class method does not get called.

What am I doing wrong here. Every other var I declare like NSArray/NSTimer, I do the say way and I am able to access and use it throughout my controller.

Answer 1

When you say "if I call it again from another function in the view controller nothing works" then first thing to check is what you are sending the testMethod . It could be nil, in which case nothing will happen. In objective C sending a message to nil does nothing. Add an NSLog to find out, eg

 NSLog(@"imageMover object is: %@", imageOver);
 [imageMover testMethod]; 

If the NSLog shows it is nil - or something crazy - then follow up what you are doing with the imageMover ivar.

You mention a class method in your question, but don't refer to it in your code snippets.

If you have defined testMethod as a class method it will, of course, fail if you send that message to an instance. (And it will fail noisily.) A class method would be introduced like this:

 + (void) testMethod
 {
       NSLog(@"CMImageMover testMethod called on Class");
 }

An instance method would be introduced like this:

 - (void) testMethod
 {
       NSLog(@"testMethod called on an instance of CMImageMover");
 }

Apologies if this is all screamingly obvious to you and missing the point of the question. It's not that clear from your question where the issue lies.