Double Tap makes crash SpriteKit Game - ios8

Question

I am new to SpriteKit game dev.
In my game when character touch enemy , it will show game over scene and restart it.
However after Game Over Scene showed, double in game is making app crash.
Here is my codes in MainGameScene.
- (void)gameOver
{
GameOver *over = [[GameOver alloc] initWithSize:self.size];
SKTransition *trans = [SKTransition flipHorizontalWithDuration:0.5];
[self.view presentScene:over transition:trans];
}
And here is GameOver Scene.
- (instancetype)initWithSize:(CGSize)size
{
self = [super initWithSize:size];
{
SKLabelNode *lblGameOver = [[SKLabelNode alloc] initWithFontNamed:#"Chalkduster"];
lblGameOver.text = #"Game Over";
lblGameOver.position = CGPointMake(self.size.width/2, self.size.height/2);
lblGameOver.fontSize = 35;
lblGameOver.fontColor = [UIColor whiteColor];
lblGameOver.zPosition = 2;
[self addChild:lblGameOver];
}
return self;
}
- (void)didMoveToView:(SKView *)view
{
[super didMoveToView:self.view];
UITapGestureRecognizer *tapper = [[UITapGestureRecognizer alloc]
initWithTarget:self action:#selector(newGame)];
[view addGestureRecognizer:tapper];
}
- (void)newGame
{
GameScene * scene = [[GameScene alloc] initWithSize:self.size];
SKTransition *trans = [SKTransition flipHorizontalWithDuration:0.5];
[self.view presentScene:scene transition:trans];
}
That make crash my app when i double tap in New Game Scene.
Error message is
Thread 1 : EXC_BAD_ACCESS (code=1,address=0x0)
How could i fix it?

Answer 1

Try this in your didMoveToView method:
UITapGestureRecognizer *tapRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(newGame)];
[self.view addGestureRecognizer:tapRecognizer];
tapRecognizer.numberOfTapsRequired = 2; // 1 for a single tap or 2 for a double tap