Question

I have a method which has gotten a little long & I want to place it in its own file. It’s not useful outside the program I’m working on, I really just want to remove it so that my code is more readable.

The method is below,

  - (void)randomiseAudioIndicesBeforeInitialPlay
{  
 int numberOfStems = 20;

 index = malloc(numberOfStems*sizeof(int));
 for (int i = 0; i < numberOfStems; i++)
 {
    index[i] = i;
 }

 for (int i = (numberOfStems - 1); i > 0; i--)
 {
    int randomIndex = arc4random() % i;
    int tmp = index[i];
    index[i] = index[randomIndex];   
    index[randomIndex] = tmp;
 }

}

I tried making a subclass as per this previous question

//RandomiseStems.h
#import <Foundation/Foundation.h>

@interface RandomiseStems : UIViewController {

int *index;

}

@property(nonatomic, readwrite) int *index;

- (void)randomiseAudioIndicesBeforeInitialPlay;

@end


//RandomiseStems.m
#import "RandomiseStems.h"

@implementation RandomiseStems
@synthesize index;

- (void)randomiseAudioIndicesBeforeInitialPlay
{  
NSLog(@"randomise called");

int numberOfStems = 20;

//int* index = malloc(numberOfStems*sizeof(int));
index = malloc(numberOfStems*sizeof(int));
for (int i = 0; i < numberOfStems; i++)
{
    index[i] = i;
}

for (int i = (numberOfStems - 1); i > 0; i--)
{
    int randomIndex = arc4random() % i;
    int tmp = index[i];
    index[i] = index[randomIndex];   
    index[randomIndex] = tmp;
    //free index
}



}

@end

I then import the .h into my viewController.h file & my .m file into my viewController.m file. It’s builds ok but when I try to call randomiseAudioIndicesBeforeInitalPlay it throws an exception (i used
[self randomiseAudioIndicesBeforeInitalPlay];)

Is this a valid way to do this? if so any ideas on how it might be fixed? thanks in advance 🙂

Answer 1

If you just want to move a method, or a few, a Category is the way to go, that is what they are designed for. What you can’t do is create any new ivars.