Question

I’m trying to get a string in my call from an array. But have no luck. It’s being passed to another class.

MainClass.h
#import First
@class First;

@interface MainClass : UIViewController{
NSMutableArray *listArray;
}
///////////////////
MainClass.m

    First *first = [[First alloc] init];

    listArray = [[NSMutableArray alloc]init];
        [listArray addObject:@"first"];
        [listArray addObject:@"second"];

    int Aslot = 0;
    int sumA;
float level = 5, insample = 10;

    NSString *slotA =[listArray objectAtIndex:ASlot];

           sumA = [slotA out:insample andlevels:level];

/////////
First.h
-(float)out:(float)insample andlevels:(float)level;

First.m
-(float)out:(float)insample andlevels:(float)level{

float outsample = insample + 10 * level;

return outsample;
}

I want slotA (the Class) to equal a string from the array “first” or “second”, so it can call the method.

I have a table which when I select first, it sends samples and other parameters to another class where it does processing then returns back to MainClass.

sumA = [first out:insample andlevels:level];

But I’m getting an error saying that NSString may not respond to my parameters out:andlevels. Please help..

Answer 1

Edit:

If I understand correctly, you want to dynamically create an instance of a class whose name you have stored as an NSString. You can do that this way:

int Aslot = 0;
int sumA;
float level = 5, insample = 10;

NSString *className = [listArray objectAtIndex:Aslot];
Class sampler = objc_getClass([className UTF8String]);
id instance = [[sampler alloc] init];
sumA = [instance out:insample andlevels:level];

// Do whatever you want with sumA here.

[instance release];

If you’re doing this a lot, you’ll probably want to either keep the instance around or store the classes in the array instead of their names, depending on exactly what you are doing.