Questions tagged [fast-enumeration]

Instead of using an NSEnumerator object or indices to iterate through a collection, Objective-C 2.0 offers the fast enumeration syntax. In Objective-C 2.0, the following loops are functionally equivalent, but have different performance characteristics.

// Using NSEnumerator
NSEnumerator *enumerator = [thePeople objectEnumerator];
Person *p; 
while ((p = [enumerator nextObject]) != nil) {
 NSLog(@"%@ is %i years old.", [p name], [p age]);

// Using fast enumeration
for (Person *p in thePeople) {
 NSLog(@"%@ is %i years old.", [p name], [p age]);
}

Fast enumeration generates more efficient code than standard enumeration because method calls to enumerate over objects are replaced by pointer arithmetic using the NSFastEnumeration protocol

Reference:
http://en.wikipedia.org/wiki/Objective-C#Fast_enumeration