NSString is empty

Question

How do you test if an NSString is empty? or all whitespace or nil? with a single method call?

Answer 1

This is what I use, an Extension to NSString:

+ (BOOL)isEmptyString:(NSString *)string;
// Returns YES if the string is nil or equal to @""
{
    // Note that [string length] == 0 can be false when [string isEqualToString:@""] is true, because these are Unicode strings.

    if (((NSNull *) string == [NSNull null]) || (string == nil) ) {
        return YES;
    }
    string = [string stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]];

    if ([string isEqualToString:@""]) {
        return YES;
    }

    return NO;  
}

Answer 2

You can try something like this:

@implementation NSString (JRAdditions)

+ (BOOL)isStringEmpty:(NSString *)string {
   if([string length] == 0) { //string is empty or nil
       return YES;
   } 

   if(![[string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] length]) {
       //string is all whitespace
       return YES;
   }

   return NO;
}

@end

Check out the NSString reference on ADC.