I am working on kiwi framework for testing by following
myStack.m
- (id) init {
    if (self = [super init]) {
        _data = [[NSMutableArray alloc] initWithCapacity:4];
    }
    return self;
}
- (void) push:(int)numberToPush {
    [self.data addObject:numberToPush];
}
- (int)top {
    return [[self.data lastObject] integerValue];
}
-(int)numberOfItem {
    return [self.data count];
}
and testing is
SPEC_BEGIN(MyStack)
describe(@"The stack", ^{
    __block MyStack    *stack;
    context(@"when created", ^{
        beforeAll(^{
            stack = [[MyStack alloc] init];
        });
        it(@"is not nil.", ^{
            [stack shouldNotBeNil];
        });
        it(@"allows me to count the item of stack", ^{
            [stack push:5];
            [[stack should] haveCountOf:1];
        });
    });
});
SPEC_END
However, I am getting BAD_EXCESS with Expectations testing.I dont know why getting this error. All helps are welcomed here. 
 
                        
It looks like you are trying to add an
intto yourNSMutableArray. You can only add objects to anNSArray, not primitive types. Try boxing in anNSNumberin your implementation ofpush::