Editing Foreach loop (section)

=== Objective-C ===
Foreach loops, called [[Objective-C#Fast enumeration|Fast enumeration]], are supported starting in [[Objective-C]] 2.0. They can be used to iterate over any object that implements the NSFastEnumeration protocol, including NSArray, NSDictionary (iterates over keys), NSSet, etc.

<syntaxhighlight lang="ObjC">
NSArray *a = [NSArray new];       // Any container class can be substituted

for(id obj in a) {                // Dynamic typing is used. The type of object stored
                                  // in 'a' can be unknown. The array can hold many different 
                                  // types of object.

    printf("%s\n", [[obj description] UTF8String]);  // Must use UTF8String with %s
    NSLog(@"%@", obj);                               // Leave as an object
}
</syntaxhighlight>

NSArrays can also broadcast a message to their members:

<syntaxhighlight lang="ObjC">
NSArray *a = [NSArray new];

[a makeObjectsPerformSelector:@selector(printDescription)];
</syntaxhighlight>

Where [[Blocks (C language extension)|blocks]] are available, an NSArray can automatically perform a block on every contained item:

<syntaxhighlight lang="ObjC">
[myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
	{
		NSLog(@"obj %@", obj);
		if ([obj shouldStopIterationNow])
			*stop = YES;
	}];
</syntaxhighlight>

The type of collection being iterated will dictate the item returned with each iteration.
For example:

<syntaxhighlight lang="ObjC">
NSDictionary *d = [NSDictionary new];

for(id key in d) {
    NSObject *obj = [d objectForKey:key];      // We use the (unique) key to access the (possibly nonunique) object.
    NSLog(@"%@", obj);
}
</syntaxhighlight>