Question

我在屏幕底部有一个图层（字符），另一层（食物）从屏幕顶部掉落。我的目标是让食物层能够在动画期间检测它与角色的交叉点，但是我很难搞清楚它。

这是我目前的代码，任何帮助都将非常感谢：

CABasicAnimation *drop = [CABasicAnimation animationWithKeyPath:@"position"];

[drop setDelegate:self];

[drop setFromValue:[NSValue valueWithCGPoint:[food position]]];

float bottomx = [food position].x;
float bottomy = [character position].y;

newPosition = CGPointMake(bottomx, bottomy);

[drop setToValue:[NSValue valueWithCGPoint:(newPosition)]];

[drop setDuration:2.0];

[food addAnimation:drop forKey:@"drop"];

[food setPosition:newPosition];


if (CGRectIntersectsRect(food.frame, character.frame)){
    NSLog(@"They touched!");

}

Answer 1

这应该让你开始。

声明属性：

@property (strong, nonatomic) CALayer *food;
@property (strong, nonatomic) CALayer *character;
@property (strong, nonatomic) NSTimer *timer;

添加以下方法：

我添加了用于测试目的的图层：

- (void)prepareLayersAndAnimation
{
    self.food = [CALayer layer];
    CGPoint newPosition;
    self.food.backgroundColor = [[UIColor greenColor] CGColor];
    self.food.frame = (CGRect){{160, 300}, 45, 45};

    self.character = [CALayer layer];
    self.character.frame = (CGRect){{160, 50}, 45, 45};
    self.character.backgroundColor = [[UIColor blueColor] CGColor];

    [self.view.layer addSublayer:self.food];
    [self.view.layer addSublayer:self.character];

    CABasicAnimation *drop = [CABasicAnimation animationWithKeyPath:@"position"];
    [drop setDelegate:self];
    [drop setFromValue:[NSValue valueWithCGPoint:[self.food position]]];

    float bottomx = [self.food position].x;
    float bottomy = [self.character position].y;
    newPosition = CGPointMake(bottomx, bottomy);
    [drop setToValue:[NSValue valueWithCGPoint:(newPosition)]];
    [drop setDuration:2.0];
    [self.food addAnimation:drop forKey:@"drop"];
    [self.food setPosition:newPosition];
}

- (void)animationDidStart:(CAAnimation *)anim
{
    self.timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(detectCollision) userInfo:nil repeats:YES];
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    [self.timer invalidate];
}

- (void)detectCollision
{
    if (CGRectIntersectsRect([[self.food presentationLayer] frame] , self.character.frame))
    {
        NSLog(@"They touched!");
        [self.timer invalidate];
    }
}

然后致电 ：

[self prepareLayersAndAnimation];

代码已经过测试。希望这可以帮助。

在动画中检测图层的交集

1 个答案: