Null True False in Objective-C

To check if a value is null in Objective-C, you can use the == operator with the keyword NULL. Here's an example:

NSString *myString = nil;
if (myString == NULL) {
    NSLog(@"The value is null.");
} else {
    NSLog(@"The value is not null.");
}

To check if a value is true or false in Objective-C, you can use the == operator with the YES or NO keywords. Here are two examples:

BOOL myBool = YES;
if (myBool == YES) {
    NSLog(@"The value is true.");
} else {
    NSLog(@"The value is false.");
}

BOOL myBool = NO;
if (myBool == YES) {
    NSLog(@"The value is true.");
} else {
    NSLog(@"The value is false.");
}

Note that YES and NO are defined as typedef'd versions of true and false in Objective-C.