NSString "nil or empty" check -- is this complete?

Question

I was writing a small Category on NSString, and I wanted to know if this method is accurately handles all potential use cases:

Update: to clarify -- I wanted to make sure I'm not missing some oddball case involving character encodings, etc..

@implementation NSString (Helpers)  +(BOOL)stringIsNilOrEmpty:(NSString*)aString {     if (!aString)         return YES;     return [aString isEqualToString:@""]; } @end 

Sample usage:

-(void) sampleUsage {     NSString *emptyString = @"";     NSString *nilString = nil;     NSAssert([NSString stringIsNilOrEmpty:nilString] == YES, @"String is nil/empty");     NSAssert([NSString stringIsNilOrEmpty:emptyString] == YES, @"String is nil/empty"); } @end 

Answer 1

I only use the next conditional and do not even need a category:

if (!aString.length) {     ... } 

Using Objective-C theory, a message to NIL will return nil or zero, so basically you do not have to test for nil.