objective c accessing public method

Question

I try to access a public method from another class. I already tried many examples I found in the web, but they didn't work in the way I wanted them to.

Class1.h

@interface anything : NSObject {

    IBOutlet NSTextField *label;

}

+ (void) setLabel:(NSString *)string;
- (void) changeLabel:(NSString *)string2;

Class1.m

+ (void) setLabel:(NSString *)string {

    Class1 *myClass1 = [[Class1 alloc] init];

    [myClass1 changeLabel:string];
    NSLog(@"setLabel called with string: %@", string);

}

- (void) changeLabel:(NSString *)string2 {

    [label setStringValue:string2];
    NSLog(@"changeLabel called with string: %@", string2);
}

Class2.m

- (IBAction)buttonPressed {

    [Class1 setLabel:@"Test"];

}

Very strange is that in the NSLogs, everything is fine, in both NSLogs, the string is "Test", but the textField's stringValue doesn't change!

Answer 1

Here a short example for what you can do:

---

The Custom Class

@interface ITYourCustomClass : NSObject
@property (strong) NSString *title;

- (void)doSomethingWithTheTitle;
@end

@implementation ITYourCustomClass
- (void)doSomethingWithTheTitle {
    NSLog(@"Here's my title: %@", self.title);
}
@end

---

Using it

@implementation ITAppDelegate

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    ITYourCustomClass *objectOfYourCustomClass = [[ITYourCustomClass alloc] init];
    [objectOfYourCustomClass doSomethingWithTheTitle];
}

@end

---

Class and object methods

Declaring a method with + means, that you can call the method directly on a class. Like you did it with [myClass1 setLabel:@"something"];. This doesn't make sense. What you want, is creating a property. A property is saved in an object, so you can create an object ITYourCustomClass *objectOfYourCustomClass = [[ITYourCustomClass alloc] init]; and setting the properties objectOfYourCustomClass.title = @"something". Then you can call [objectOfYourCustomClass doSomethingWithTheTitle];, which is a public object method.

Answer 2

- and + don't mean public or private

- stands for methods that you can call on objects of the class and

+ stands for methods that can be called on the class itself.

Answer 3

You're trying to access an instance variable with a class method. You should convert the +setLabel: method to -setLabel:, and call it like this:

[_myClass1Variable setLabel:@"Test"];

Additionally, what's -setStringValue? If you're just trying to change the text of the UILabel you need to call -setText:.

Answer 4

I guess label would be a NSTextField, and you are tring to set its value without loading that XIB, resulting that your awakeFromNib is not getting called. And the outlet will not be bound that that label.