objective c - Get String From Array to call method -

i'm trying string in call array. have no luck. it's being passed 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) equal string array "first" or "second", can call method.

i have table when select first, sends samples , other parameters class processing returns mainclass.

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

but i'm getting error saying nsstring may not respond parameters out:andlevels. please help..

edit:

if understand correctly, want dynamically create instance of class name have stored nsstring. can 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];  // whatever want suma here.  [instance release]; 

if you're doing lot, you'll want either keep instance around or store classes in array instead of names, depending on doing.