Objective-C Default Argument Value

Question

Hey there, quick question here. I\'m sure there\'s a simple answer.

Coming from PHP, I\'m used to declaring a function with a default argument value like this:

Answer 1

Terrible necro but for anyone googling this, Xcode 4.5 supports (via Clang) overloading of C functions with __attribute__((overloadable)).

Overloaded functions are allowed to have different numbers of arguments, so if C functions are appropriate for what you're trying to do you can use that to get default argument values.

Here's a contrived example of an .h file with two functions, both called PrintNum:

// Prints a number in the decimal base
__attribute__((overloadable)) extern void PrintNum(NSNumber *number);

// Prints a number in the specified base
__attribute__((overloadable)) extern void PrintNum(NSNumber *number, NSUInteger base);

and in the .m file:

__attribute__((overloadable)) 
void PrintNum(NSNumber *number) {
    PrintNum(number, 10);
}

__attribute__((overloadable))
void PrintNum(NSNumber *number, NSUInteger base) {
    // ...
}

Note that the attribute must be specified in all definitions and declarations of the function.