Mac OS X Leopard - ARCAism

- (void)privateMethod;
{
[self privateHelper];
// ...
}
- (void)privateHelper;
{
// ...
}
@end
NOTE Class extensions, unlike protocols, are completely anonymous and cannot be adopted
by multiple classes.
Fast Enumeration
CHAPTER 26 MAC OS X DEVELOPMENT: OBJECTIVE-C 505
Iterating over a collection is one of the most common tasks in programming. Traditionally, C
accomplishes this via the standard for loop:
NSArray *objects = [self methodThatReturnsAnArrayOfObjects];
NSUInteger objectIndex;
for (objectIndex = 0; objectIndex < [objects count]; objectIndex++) {
NSObject *object = [objects objectAtIndex:objectIndex];
// ...
}
This is effective, but it’s a lot to type, it requires an additional method call, and worst of all
it works only for arrays. As such, Cocoa provides the NSEnumerator class, which enables the following:
NSArray *objects = [self methodThatReturnsAnArrayOfObjects];
NSEnumerator *objectEnumerator = [objects objectEnumerator];
NSObject *object = nil;
while ((object = [objectEnumerator nextObject])) {
// ...
}
For all the object-oriented goodness that enumerators bring, they are slow and require
making a copy of every object. They also suffer from the same kind of redundant verbosity as the
C iteration loop. Objective-C 2.0 introduces the ultimate solution to the looping problem:
NSArray *objects = [self methodThatReturnsAnArrayOfObjects];
for (NSObject *object in objects) {
// ...
}
Fast enumeration is both more concise and more readable than either of the other methods.
It is backed by the NSFastEnumeration protocol, so it can work with any collection, including your
own. It is also highly optimized, so it is not only faster than traditional enumeration, but it is also
faster than C iteration.
Finally, fast enumeration adds the benefit of a mutation check, which ensures collections do
not change during enumeration. This makes it possible to perform multiple enumerations simultaneously.
This is part of a general move toward thread safety as multiprocessor technology
continues to form an important part of the platform.