Enumeration in Objective-C classes

Fast enumeration in Objective-C is a construct which allows to enumerate the elements in a Cocoa container class in a generic way. It is implemented using a for-in loop in Objective-C.

This has been translated to Objective-Pascal using the existing for-in loop mechanism. Therefor, the feature behaves identically in both languages. Note that it requires the Objective-C 2.0 mode switch to be activated.

{$mode delphi}
{$modeswitch objectivec2}

uses
  CocoaAll;

var
  arr: NSMutableArray;
  element: NSString;
  pool: NSAutoreleasePool;
  i: longint;
begin
  pool:=NSAutoreleasePool.alloc.init;
  arr:=NSMutableArray.arrayWithObjects(
    NSSTR(’One’),
    NSSTR(’Two’),
    NSSTR(’Three’),
    NSSTR(’Four’),
    NSSTR(’Five’),
    NSSTR(’Six’),
    NSSTR(’Seven’),
    nil);

  i:=0;
  for element in arr do
    begin
      inc(i);
      if i=2 then
        continue;
      if i=5 then
        break;
      if i in [2,5..10] then
        halt(1);
      NSLog(NSSTR(’element: %@’),element);
    end;
  pool.release;
end.

11.10 Enumeration in Objective-C classes