How to test whether NSString in Objective-C is empty?

#1 building

In any case, the best way is to check the length of a given string. If your string is myString, the code is:

    int len = [myString length];
    if(len == 0){
       NSLog(@"String is empty");
    }
    else{
      NSLog(@"String is : %@", myString);
    }

#2 building

Just use one of the if else conditions as follows:

Method 1:

if ([yourString isEqualToString:@""]) {
        // yourString is empty.
    } else {
        // yourString has some text on it.
    }

Method 2:

if ([yourString length] == 0) {
    // Empty yourString
} else {
    // yourString is not empty
}

#3 building

Very useful article with NSDictionary support and a small change

static inline BOOL isEmpty(id thing) {
    return thing == nil
    || [thing isKindOfClass:[NSNull class]]
    || ([thing respondsToSelector:@selector(length)]
        && ![thing respondsToSelector:@selector(count)]
        && [(NSData *)thing length] == 0)
    || ([thing respondsToSelector:@selector(count)]
        && [thing count] == 0);
}

#4 building

The first method is valid, but not if your string has spaces (@ ""). Therefore, you must clear this blank before testing.

This code clears all spaces on both sides of the string:

[stringObject stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet] ];

A good idea is to create a macro, so you don't have to type the following monster line:

#define allTrim( object ) [object stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet] ]

Now you can use:

NSString *emptyString = @"   ";

if ( [allTrim( emptyString ) length] == 0 ) NSLog(@"Is empty!");

#5 building

It's glamour for me

If NSString is s

if ([s isKindOfClass:[NSNull class]] || s == nil || [s isEqualToString:@""]) {

    NSLog(@"s is empty");

} else {

    NSLog(@"s containing %@", s);

}