xcode - how to get NSObject values -

i have nsobject 3 diferents fields :

myobject : {  title : bar4343; iduser : 4; type : class1;  } 

i try value doing

str = [myobject ojectforkey:@"title"]; // try value nsstring 

i error :

no visible @interface 'nsobject' declares de selector 'objectforkey'

please, what's wrong, can me ?

thanks

i think need change code :

myobject *myobject;  // add code object  // value : str = myobject.title;