How do i keep my code organised when my app needs a helper class? - iphone

Question

I have a few custom UIViewControllers in my app which need to know the string returned of an NSDate. I could copy and paste the same code between these classes, but that's obviously terrible practise. It's also probably not good to put it in 1 class as a method, then have another class add this class to take advantage of it's method. It seems like a messy thing to do. So what would you recommend i do?
To clarify - I need a method which is given an NSDate and returns a string, for use in several other classes.

Answer 1

Sounds like you either need a function, rather than a method:
//Helpers.h
#import <Foundation/Foundation.h>
NSString * makeAStringFromThisDateSomehow(NSDate * d);
//Helpers.m
#import "Helpers.h"
NSString * makeAStringFromThisDateSomehow(NSDate * d)
{
// Body
// of
// your
// function
}
Or to make a category on NSDate to do what you need:
//NSDate+AndrewsCategory.h
#import <Foundation/Foundation.h>
#interface NSDate(AndrewsCategory)
- (NSString *)Andrew_MakeAStringSomehow;
#end
//NSDate+AndrewsCategory.m
#import "NSDate+AndrewsCategory.h"
#implementation NSDate(AndrewsCategory)
- (NSString *)Andrew_MakeAStringSomehow {
// Body
// of
// your
// method
}
#end
Note the stupid prefix on the method name. That's important to keep your method names from colliding with other method names on framework classes. Usually you would use initials: your company's, yours, or the project's.
In either case, just import the relevant header where you need to use the function or method, and you should be hunky-dory.

Answer 2

I'd consider writing a category on NSDate. Categories let you extend the functionality of existing classes with additional methods without having to mess with the existing implementation of the class. So you can add yourMethod to NSDate, and in the future just be able to call [yourDate yourMethod].
To do this in Xcode, just hit ⌘N to create a new file, and choose Objective-C category, then give it some name and make it a category on NSDate.
Then set up your header:
#interface NSDate (YourCategory)
- (NSString *) yourMethod;
#end
And your implementation:
#implementation NSDate (YourCategory)
- (NSString *) yourMethod {
return [NSString stringWithFormat:#"yourMethod on this date: ", [self description]]; // for example
}
#end
Then just include "NSDate+YourCategory.h" in any file where you want to use yourMethod.

Answer 3

i'd recommend adding the method to a catagory and then adding the header to your projects pch file
#ifdef __OBJC__
#import "yourHeader.h"
#endif
if you google for NSDate+Helper that should give you an idea of the implementation.
Nik

Answer 4

It's probably good to put it in 1 class as a method, then have another class add this class to take advantage of it's method.
simple 1 or 2 methods NSObject subclasses won't make slightest differences in execution