UICaboodle/UCYield.h

   1 @interface NSObject (UICaboodle)
   2 - (id) yieldToSelector:(SEL)selector withObject:(id)object;
   3 - (id) yieldToSelector:(SEL)selector;
   4 @end
   5
   6 @implementation NSObject (UICaboodle)
   7
   8 - (void) doNothing {
   9 }
  10
  11 - (void) _yieldToContext:(NSMutableArray *)context { _pooled
  12     SEL selector(reinterpret_cast<SEL>([[context objectAtIndex:0] pointerValue]));
  13     id object([[context objectAtIndex:1] nonretainedObjectValue]);
  14     volatile bool &stopped(*reinterpret_cast<bool *>([[context objectAtIndex:2] pointerValue]));
  15
  16     /* XXX: deal with exceptions */
  17     id value([self performSelector:selector withObject:object]);
  18
  19     NSMethodSignature *signature([self methodSignatureForSelector:selector]);
  20     [context removeAllObjects];
  21     if ([signature methodReturnLength] != 0 && value != nil)
  22         [context addObject:value];
  23
  24     stopped = true;
  25
  26     [self
  27         performSelectorOnMainThread:@selector(doNothing)
  28         withObject:nil
  29         waitUntilDone:NO
  30     ];
  31 }
  32
  33 - (id) yieldToSelector:(SEL)selector withObject:(id)object {
  34     /*return [self performSelector:selector withObject:object];*/
  35
  36     volatile bool stopped(false);
  37
  38     NSMutableArray *context([NSMutableArray arrayWithObjects:
  39         [NSValue valueWithPointer:selector],
  40         [NSValue valueWithNonretainedObject:object],
  41         [NSValue valueWithPointer:const_cast<bool *>(&stopped)],
  42     nil]);
  43
  44     NSThread *thread([[[NSThread alloc]
  45         initWithTarget:self
  46         selector:@selector(_yieldToContext:)
  47         object:context
  48     ] autorelease]);
  49
  50     [thread start];
  51
  52     NSRunLoop *loop([NSRunLoop currentRunLoop]);
  53     NSDate *future([NSDate distantFuture]);
  54
  55     while (!stopped && [loop runMode:NSDefaultRunLoopMode beforeDate:future]);
  56
  57     return [context count] == 0 ? nil : [context objectAtIndex:0];
  58 }
  59
  60 - (id) yieldToSelector:(SEL)selector {
  61     return [self yieldToSelector:selector withObject:nil];
  62 }
  63
  64 @end