碰撞的两种实现，

-(void)checkAttack

{

static BOOL beforeState;

static int count = 0;

BOOL attack = CGRectIntersectsRect(self.lifeView.frame, self.blockView.frame);

if (beforeState == 0 && attack == 1) {

count ++;

[self.countLabel setText:[NSString stringWithFormat:@"碰撞次数：%d",count]];

}

beforeState = attack;

CGFloat blockOriginY = self.lifeView.frame.origin.y - self.blockView.frame.size.height;

CGFloat maxBlockOriginY = self.lifeView.frame.origin.y + self.blockView.frame.size.height;

CGFloat lifeOriginX = self.blockView.frame.origin.x - self.lifeView.frame.size.width;

CGFloat maxLifeOriginX = self.blockView.frame.origin.x + self.lifeView.frame.size.width;

if ((maxLifeOriginX > self.lifeView.frame.origin.x &&  self.lifeView.frame.origin.x> lifeOriginX) && (self.blockView.frame.origin.y > blockOriginY && maxBlockOriginY > self.blockView.frame.origin.y)) {

count ++;

[self.countLabel setText:[NSString stringWithFormat:@"碰撞次数：%d",count]];

}

}