iOS開發(fā)筆記之多點(diǎn)觸控（三）調(diào)用UITouch對象方法——locationInView，多點(diǎn)移動多個對象

2019-11-14 20:43:04

字體：大中小

供稿：網(wǎng)友

屏幕上新建兩個view，實(shí)現(xiàn)兩個手指在屏幕上移動兩個view，通過規(guī)則約束兩個view的活動范圍。

關(guān)鍵在于調(diào)用UITouch對象的方法——lacationInView。此方法返回View的相對于根視圖的觸摸位置。返回值是一個CGPoint類型，是一個包含X坐標(biāo)和Y坐標(biāo)的結(jié)構(gòu)體。我讓兩個view在屏幕上下兩個半?yún)^(qū)水平移動。利用CGPointMake來快速初始化新的CGPoint結(jié)構(gòu)體。

- (void)viewDidLoad{    [super viewDidLoad];    self.view.multipleTouchEnabled = TRUE;    // Do any additional setup after loading the view, typically from a nib.    _view1 = [[UIView alloc] initWithFrame:CGRectMake(0, 40, 40, 40)];    _view1.backgroundColor = [UIColor blueColor];    [self.view addSubview:_view1];        _view2 = [[UIView alloc] initWithFrame:CGRectMake(0, self.view.frame.size.height - 60, 40, 40)];    _view2.backgroundColor = [UIColor yellowColor];    [self.view addSubview:_view2];}-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event //首次在屏幕上檢測到觸摸時調(diào)用{    NSLog(@"touchesBegan");    for (UITouch *touch in touches)    {//        NSLog(@" - %p",touch);        //獲取根視圖內(nèi)觸摸點(diǎn)的point        CGPoint touchPoint = [touch locationInView:self.view];        //約束兩個view的活動范圍        if (touchPoint.y < self.view.frame.size.height/2)        {            _view1.center = CGPointMake(touchPoint.x, _view1.center.y);        }else        {            _view2.center = CGPointMake(touchPoint.x, _view2.center.y);        }    }}//以上對觸摸進(jìn)行了初始化，并未處理沿著屏幕移動的觸摸。所以，只需要在touchesMoved方法里調(diào)用touchesBegan的處理方法來改寫移動球拍的邏輯即可。-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event //如果觸摸移動到了新的位置則會調(diào)用此方法{    NSLog(@"touchesMoved");    for (UITouch *touch in touches)    {//        NSLog(@" - %p",touch);        [self touchesBegan:touches withEvent:event];    }}-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event//當(dāng)觸摸離開屏幕調(diào)用此方法{    NSLog(@"touchesEnded");    for (UITouch *touch in touches)    {        NSLog(@" - %p",touch);    }}-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event//如系統(tǒng)決定取消此次觸摸，那可能就不調(diào)用touchesEnded方法了，在這種情況下會調(diào)用touchesCancelled方法{    NSLog(@"touchesCancelled");    for (UITouch *touch in touches)    {        NSLog(@" - %p",touch);    }}