Question

Is it possible to do negative loc in the NSMakeRange?

NSString *string = @"abc";
NSString *myString = [string substringWithRange:NSMakeRange(-1, 1)];

Answer 1

No.

location and length are unsigned integers :

typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;

and also, NSMakeRange function is defined as follow :

NSRange NSMakeRange (
    NSUInteger loc,
    NSUInteger len
);