Question

I have a string

NSString hi;

and I don’t know what values will get initialized to it. Could be nil, could be empty string, could be anything.

Are there any advantages to using

if (![hi length])

vs

if (![hi isEqualToString:@""])

It seems like both cases return the same values for empty string, nil, and any other type of string. I would guess length is better because it’s more efficient. It just returns a variable, where as isEqualToString has to do a comparison.

Answer 1

They don’t do the same thing.

[hi length] will return 0 for nil or an empty string and nonzero for any other string.

[hi isEqualToString:@""] will return 1 when hi is an empty string and 0 when hi is nil or any non-empty string.

In other words, the only value of hi for which the two lines of code give the same result is nil.

You probably wanted the behavior of option #1 (treating either nil or an empty string as “blank” and any other value as “not blank”), so that would be the one to use.