CODEWITHSUNDEEP
iosobjective-c
Zingam
Zingam

Reputation: 4636

Firguring out reasons for exceptions in Objective-C

After I completed the tutorial: Start Developing iOS Apps Today

I got the same exception asked here: IOS Tutorial Exception (ToDo Sample) and the app crashed but it would not crash if I started a debugging session and stepped through the code.

2015-05-04 16:09:51.569 ToDoList[9223:67681] -[AddToDoItemViewController textField:]: unrecognized selector sent to instance 0x7fe570d4eff0
2015-05-04 16:09:51.574 ToDoList[9223:67681] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[AddToDoItemViewController textField:]: unrecognized selector sent to instance 0x7fe570d4eff0'

Then I solved the mystery by reading out this post: IOS Tutorial Exception (ToDo Sample)

The reason was that I wrongly connected the text field to the @implemenation section instead of to the @interface section and it created some method that I deleted. Of course I forgot about that soon after that.

How could I have figured out myself without knowing anything of the above what was the reason to get that exception and where it came from?

Upvotes: 0

Views: 98

Answers (2)

Jakub Vano
Jakub Vano

Reputation: 3873

Log message is telling you that something was trying to call -textField: method of your AddToDoItemViewController.

So the first step would be to check if that method is implemented - in your case it was not. You might have been confused by the presence of 

@property(weak, nonatomic) IBOutlet UITextField* textField

but auto synthesis for property generates getter with the signature -textField, which is different from -textField: (latter takes one parameter, while former none).

Upvotes: 2

pteofil
pteofil

Reputation: 4163

The exception says that you're trying to access the textView property of AddToDoItemViewController, but it doesn't have one.

So your next step would've been to go and check that you have a property like that declared and being an outlet that it's properly connected in the Interface Builder.

Edit: Sorry I wasn't paying enough attention. The selector that it's trying to call is textField: so it must be a function starting like that. I assume you set the controller as a TextView delegate but didn't implement the required method.

Upvotes: 0

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