Objective-C convenience methods for abstracting timing dependency

gistfile1.m

- (void)example
{
  NSTextView * console = [self xcodeConsoleIn: IDEWindow];
  NSInteger baseLength = [[console string] length] + [command length];
  
  [_log appendFormat: @"\n Writing into console: %@", command];

  [console insertText: command];
  [console insertNewline:nil];

  [self waitFor:@"the console to write" waitBlock:^BOOL{
      // Wait until the console text has grown to include the command
      NSInteger newLength = [[console string] length];
      if (newLength < baseLength)
          return NO;
      
      // Wait until the console has printed (lldb) indicating it's
      // ready for the next input.
      if ([[[console string] substringFromIndex: baseLength] rangeOfString: @"(lldb)"].location == NSNotFound)
          return NO;
      
      // proceed to ready block
      return YES;
      
  } readyBlock:^{
      NSString * newText = [self contentsOf:console after: baseLength];
      [_log appendFormat: @"\n Read from console: %@", newText];
      callback(newText);
  }];
}


- (void)waitFor:(NSString*)description waitBlock:(BOOL(^)())conditionalBlock readyBlock:(void(^)())finalBlock
{
    [self waitFor:description waitBlock:conditionalBlock readyBlock:finalBlock tries: 40];
}

- (void)waitFor:(NSString*)description waitBlock:(BOOL(^)())conditionalBlock readyBlock:(void(^)())finalBlock tries:(int)remaining
{
    if (remaining == 0)
        return [self showAlert: [NSString stringWithFormat: @"Setup did not complete successfully. The Spark Inspector timed out waiting for %@.", description]];
    
    [self after:INTERFACE_POLL_INTERVAL execute:^{
        if (conditionalBlock()) {
            if (finalBlock)
                finalBlock();
            return;
        }
        
        [self waitFor:description waitBlock:conditionalBlock readyBlock:finalBlock tries: remaining - 1];
    }];
}


- (void)after:(NSTimeInterval)interval execute:(void(^)())block
{
    double delayInSeconds = interval;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
        block();
    });
}