CODEWITHSUNDEEP
iospreprocessor
Bernd Rabe
Bernd Rabe

Reputation: 790

Change #define argument

I'd wrote a preprocessor define statement for a getter method

#define GetNSStringDefaultForPropertyWithNameAndKey(propertyName, propertyKey) - (NSString *)propertyName { return [[NSUserDefaults standardUserDefaults] objectForKey:_userDefaultsKey][propertyKey];  }

but got stuck when doing the same for the setter method as I'd have to modify propertyName argument to setPropertyName.

Is there way to do this kind of argument modification.

EDIT I should have said that both definitions should overwrite the compiler generated getter/setter methods. But if I got Matthias right, the only way is to provide a capitalized version of the property in question like so. 

#define SetNSStringDefaultForPropertyWithNameAndKey(PropertyName, propertyKey) - (void)set  ## PropertyName:(NSString *)newValue \  
{ \  
    self.userDefaults[propertyKey] = newValue; \
    [self updateUserDefaults]; \
} \

Upvotes: 0

Views: 137

Answers (1)

Matthias Bauch
Matthias Bauch

Reputation: 90117

You can use ## to concatenate two tokens together. However the preprocessor can't change the case of a token. So you have to provide a uppercase property name yourself.

Something like this should work

#define SetNSStringDefaultForPropertyWithNameAndKey(propertyName, propertyKey) - (void)set ## propertyName:(id)object { [[NSUserDefaults standardUserDefaults] objectForKey: _userDefaultsKey][propertyKey] = object; }

And because the preprocessor can't change to uppercase you have to provide the property name with the first letter capitalized

SetNSStringDefaultForPropertyWithNameAndKey(Foobar, @"foobar")

GetNSStringDefaultForPropertyWithNameAndKey(foobar, @"foobar")

Upvotes: 1

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