Fast Enumeration

Fast enumeration of an NSArray

This example shows how to use fast enumeration in order to traverse through an NSArray.

When you have an array, such as

NSArray *collection = @[@"fast", @"enumeration", @"in objc"];

You can use the for ... in syntax to go through each item of the array, automatically starting with the first at index 0 and stopping with the last item:

for (NSString *item in collection) {
    NSLog(@"item: %@", item);
}

In this example, the output generated would look like

// item: fast
// item: enumeration
// item: in objc

Fast enumeration of an NSArray with index.

This example shows how to use fast enumeration in order to traverse through an NSArray. With this way you can also track current object’s index while traversing.

Suppose you have an array,

NSArray *weekDays = @[@"Monday", @"Tuesday", @"Wednesday", @"Thursday", @"Friday", @"Saturday", @"Sunday"];

Now you can traverse through the array like below,

[weekDays enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {

    //... Do your usual stuff here

    obj  // This is the current object
    idx  // This is the index of the current object
    stop // Set this to true if you want to stop

}];