Question

So I have a generic question. I have a bunch of functions, some of which are void, some which return NSString*, some which return NSDictionary*, etc. I use these functions in a bunch of different classes. I want to just create a library .m file that I can include in the classes that use them, so I don’t have to copy and paste these functions all over the place. I’m pretty sure this shouldn’t be hard to do but I can’t seem to get this to work for anything but void functions.

Example:

//Library.h
(NSString*)doStuff{
    NSString* test = "hello world";
    return test;
}

(void)print{
    NSLog(@"Hi");
}

I wish to basically have 1 file that I can just use an import statement on, but am uncertain if this is possible in obj c.

Robin

Answer 1

You can use the plain old C style:

// ======== yourlib.h =========
#import <Foundation/Foundation.h>
NSString *doStuff();
void print();


//======== yourlib.m =========
#import "yourlib.h"
NSString *doStuff(){
    NSString *test = @"hello world";
    return test;
}

void print(){
    NSLog(@"Hi");
}

Or, you can use the category feature to attach to existing frameworks:

// ======= youlib.h ========
#import <Foundation/Foundation.h>
@interface NSString (YourCategory)
+ (NSString *)someStringFromString:(NSString*)string;
- (NSDictionary *)someDictionaryFromString;
@end
// ======= yourlib.m =======
#import "yourlib.h"
@implementation NSString(YourCategory)
+ (NSString *)someStringFromString:(NSString*)string {
   ...
   return aString;
}
- (NSDictionary *)someDictionaryFromString {
   ...
   return aDict;
}
@end