CODEWITHSUNDEEP
objective-ciosmethods
blueStar
blueStar

Reputation: 313

Undeclared Method Error Objective C IOS

i am new to Obejctive C, so please forgive me if this is a simple question. i am trying to get the below code to work (from the Facebook IOS integration tutorial),but i get an error at the line 

- (void) logoutButtonClicked:(id)sender {
    [facebook logout];

I get the error

"use of undeclared identifier" logoutButtonClicked. I know that this is saying i am implementing a method that is not defined. So my question is, where is the method being defined in the code below?

i have seen a solution here posted but it does not work for me, this error persists. I have tried alternatives to try and fix, but could some one please confirm what this block of code is doing.

My understanding is that, we start of creating a pointer (logoutButton) to UIButton, and we then set the parameters of it. We then use a selector to define an action message (LogoutButtonClicked), for the method UIControlEventTouchInside.

I don't fully understand how the method is being declared, because I thought that the line here is defining the instance method: 

-(void) logoutButtonClicked:(id)sender {
        [facebook logout];

Or is the method being declared in 

[logoutButton addTarget:self action:@selector(logoutButtonClicked)
           forControlEvents:UIControlEventTouchUpInside];

// Add the logout button
    UIButton *logoutButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    logoutButton.frame = CGRectMake(40, 40, 200, 40);
    [logoutButton setTitle:@"Log Out" forState:UIControlStateNormal];
    [logoutButton addTarget:self action:@selector(logoutButtonClicked)
           forControlEvents:UIControlEventTouchUpInside];
    [self.viewController.view addSubview:logoutButton];
    // Method that gets called when the logout button is pressed
    - (void) logoutButtonClicked:(id)sender {
        [facebook logout];
    }

i would really appreciate someones help on this , have been struggling with trying to understand this to no avail.

Melvin

Upvotes: 1

Views: 341

Answers (2)

Ken Thomases
Ken Thomases

Reputation: 90551

You appear to be defining a method right smack in the middle of another method. You can't do that. The lines:

- (void) logoutButtonClicked:(id)sender {
    [facebook logout];
}

have to appear outside of any other method, not within the curly braces ({ ... }) of another method.

Upvotes: 2

justin
justin

Reputation: 104698

The colon is part of the selector's name:

@selector(logoutButtonClicked:)
                             ^

NOT

@selector(logoutButtonClicked)

Upvotes: 3

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