Question

I have

enum Colour {
    white,
    pink,
    yellow,
    blue
} Colour;

And I would like to do something like this:

for (int colour in Colour) {
    // Do something here.
}

Can I do this and if yes, how?

Answer 1

An enum comes from, C while fast enumeration was an addition of Objective-C 2.0… They don’t work together.

Type existingItem;
for ( existingItem in expression ) { statements }

An expression must conform to the NSFastEnumeration Protocol and be an Object! "elements" of an enum are not objects.

See Apple’s Fast Enumeration Documents for more information.

Check this example to see how fast enumeration works:

NSArray *array = [NSArray arrayWithObjects:
        @"One", @"Two", @"Three", @"Four", nil];

for (NSString *element in array) {
    NSLog(@"element: %@", element);
}

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:
    @"quattuor", @"four", @"quinque", @"five", @"sex", @"six", nil];

NSString *key;
for (key in dictionary) {
    NSLog(@"English: %@, Latin: %@", key, [dictionary objectForKey:key]);
}