Basic objective-c question re comparisons in if statement

Question

I feel embarrassed asking this, but it seems like something I need to understand:

Why does this evaluate to true? (if I cast it to int it properly evaluates to false)

NSString *var1 = @"ABC";
NSString *var2 = @"ABCD";

if (([var1 length] - [var2 length]) > 2) NSLog(@"-1 > 2");

Answer 1

length is unsigned.

See docs:

length
Returns the number of Unicode characters in the receiver.

- (NSUInteger)length

Return Value
The number of Unicode characters in the receiver.