Question

If statetement : I found something strange. Why does my second ‘if’ is equal to no?

    int a = bookSettings.tracks.count;
    int b = _currentChapter - 1;
    NSLog(@"a: %d", a);
    NSLog(@"b: %d", b);

    if (a > b) 
        NSLog(@"yes 1");
    else NSLog(@"no 1");        

    if (bookSettings.tracks.count > (_currentChapter -1)) 
        NSLog(@"yes 2");        
    else NSLog(@"no 2");   

and log

a: 27
b: -1
yes 1
no 2

Answer 1

NSArray’s -count method returns an NSUInteger — an unsigned integer.

Using bookSettings.tracks.count in your if statement is likely causing both sides of the expression to be cast as NSUInteger. Even though _currentChapter - 1 equals -1, as an unsigned integer it is a very large number. So your track count is obviously less than that very large integer, which is why the if statement is yielding “no 2”.