CODEWITHSUNDEEP
objective-cios
user1190646
user1190646

Reputation:

Objective C - Can't work out @property/@synthesize setters and getters?

I know this is a newbie question but i can't get my head around this (or really, i can't get it working)

so i have in my .h

@interface
NSString *test;
@end;

@property NSString *test

and in my .m

...
@synthesize test;
...

but i want a custom setter for test - what is the correct syntax?

thanks

Upvotes: 1

Views: 2440

Answers (3)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726987

First, you do not need to declare a variable test if you plan to @synthesize, but if you do, you need to put it in curly braces.

Second, the declaration of the property needs to be inside the interface:

@interface {
    NSString *test;
}
@property (readwrite) NSString *test
@end;

Finally, the syntax for the setter is

-(void)setTest:(NSString*)test {
    ...
}

If you choose to override the getter as well, the convention is

-(NSString*)test {
    return test;
}

Upvotes: 2

dreamlax
dreamlax

Reputation: 95365

If your custom setter has a method name that is different to setTest: (assuming the property name is test), you can specify the setter using:

@property(readwrite,setter=setShokolokobangoshay:) NSString *test;

Then if you have:

object.test = @"SomeValue";

It will automatically “translate” to:

[object setShokolokobangoshay:@"SomeValue"];

Otherwise, you can simply provide a setTest: method and it will automatically be used as the setter for the property, even if you use the @synthesize directive (in which case, the @synthesize directive will only implement a getter).

Upvotes: 1

Xono
Xono

Reputation: 1910

Simple create a method with the definition

- (void) setTest:(NSString*) new_value

This is the method that will be called when you attempt to modify the value of the test property (you can alter this as appropriate for other property names).

Remember that this method will only be called when you attempt to modify self.test (the property) - if you modify the test variable directly, this will not call setTest. It's good practise to name your non-property variable something else (preceding with an underscore _test is common), and have your synthesize statement refer to it:

@synthesize test = _test;

This will have accessing self.test get the value of _test, and modifying self.test call your setTest method. If you want to override the getter, this has the definition

- (NSString*) test

Upvotes: 1

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