通過UISwipeGestureRecognizer更改UISlider值

Question

我試圖通過UISwipeGestureRecognizer更改滑塊值，但是看來我的代碼不起作用！ 我正在使用此代碼：

- (void)viewDidLoad
{

    [super viewDidLoad];

    UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(didSwipe:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight)];
    [self.view addGestureRecognizer:recognizer];


    recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(didSwipe:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionLeft)];
    [self.view addGestureRecognizer:recognizer];
    recognizer.delegate = self;

}


- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch {
    if ([touch.view isKindOfClass:[UISlider class]]) {
        // prevent recognizing touches on the slider
        return NO;
    }

    return YES;
}



- (void) didSwipe:(UISwipeGestureRecognizer *)recognizer{
    if([recognizer direction] == UISwipeGestureRecognizerDirectionLeft){

        NSLog(@"left");

         _label.text = [NSString stringWithFormat:@"%f",_slider.value];

        }else{

         NSLog(@"right");
    }
}

它只是將值更改為0.0，就像滑動一些東西一樣！

Answer 1

在didSwipe：方法中，您只顯示值，而不嘗試更改它。 用如下代碼替換您的代碼：

- (void) didSwipe:(UISwipeGestureRecognizer *)recognizer{
    if([recognizer direction] == UISwipeGestureRecognizerDirectionLeft){

        NSLog(@"left");

         _label.text = [NSString stringWithFormat:@"%f",_slider.value];
         // TODO: make sure that the value is not less than min slider value
         _slider.value = _slider.value - 5;

        }else{
         // TODO: make sure that the value is not larger than max slider value
         _slider.value = _slider.value + 5;
         NSLog(@"right");
    }
}

另外，為了實現最佳化，您可以只用一個替換兩個手勢識別器：

    UISwipeGestureRecognizer *recognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(didSwipe:)];
    [recognizer setDirection:(UISwipeGestureRecognizerDirectionRight | UISwipeGestureRecognizerDirectionLeft)];
    recognizer.delegate = self;
    [self.view addGestureRecognizer:recognizer];