iPhone编程中如何在UISlider上设置滑块到点击位置并获取点击位置上的滑块值。我知道我们可以将滑块拖动到那个位置,但我不想这样做。你能告诉我如何将滑块设置到点击位置吗?这可能吗?
6 回答
这是“留作用户练习”的部分:
- (void) tapped: (UITapGestureRecognizer*) g {
UISlider* s = (UISlider*)g.view;
if (s.highlighted)
return; // tap on thumb, let slider deal with it
CGPoint pt = [g locationInView: s];
CGFloat percentage = pt.x / s.bounds.size.width;
CGFloat delta = percentage * (s.maximumValue - s.minimumValue);
CGFloat value = s.minimumValue + delta;
[s setValue:value animated:YES];
}
我这样做的方法是对滑块进行子类化并签入touchesBegan
. 如果用户点击拇指按钮区域(我们跟踪)然后忽略点击,但我们会在轨迹栏上的任何其他位置::
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchLocation = [touch locationInView:self];
// if we didn't tap on the thumb button then we set the value based on tap location
if (!CGRectContainsPoint(lastKnownThumbRect, touchLocation)) {
self.value = self.minimumValue + (self.maximumValue - self.minimumValue) * (touchLocation.x / self.frame.size.width);
}
[super touchesBegan:touches withEvent:event];
}
- (CGRect)thumbRectForBounds:(CGRect)bounds trackRect:(CGRect)rect value:(float)value {
CGRect thumbRect = [super thumbRectForBounds:bounds trackRect:rect value:value];
lastKnownThumbRect = thumbRect;
return thumbRect;
}
您可以简单地向滑块添加一个 UITapGestureRecognizer,然后拉出与之关联的 UIEvent 和 Touches 以找出沿着 UISlider 发生点击的位置。然后将滑块的值设置为此计算值。
更新:
首先,设置您的滑块并向其添加手势识别器。
UISlider *slider = [[[UISlider alloc] init] autorelease];
…
<slider setup>
…
UITapGestureRecognizer *gr = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(sliderTapped:)] autorelease];
[slider addGestureRecognizer:gr];
然后实现选择器
- (void)sliderTapped:(UIGestureRecognizer *)gestureRecognizer {
<left as a user excercise*>
}
*提示:阅读文档以了解如何推断 locationInView 并确定滑块应该是什么
似乎只是继承 UISlider 并始终返回 true 到 beginTracking 会产生所需的效果。
iOS 10 和 Swift 3
class CustomSlider: UISlider {
override func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool {
return true
}
}
我使用子类 UISlider 代码来监听 ios6> 中的 ValueChanged 事件,以实现对齐网格类型的函数。
这在升级到 iOS7 时被破坏,因为它不再触发 UIControlEventsValueChanged。对于遇到相同问题的任何人,可以通过在 if() 中添加一行来解决,如下所示:
-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
CGPoint touchLocation = [touch locationInView:self];
// if we didn't tap on the thumb button then we set the value based on tap location
if (!CGRectContainsPoint(lastKnownThumbRect, touchLocation)) {
self.value = self.minimumValue + (self.maximumValue - self.minimumValue) * (touchLocation.x / self.frame.size.width);
[self sendActionsForControlEvents:UIControlEventValueChanged];
}
[super touchesBegan:touches withEvent:event];
}
- (CGRect)thumbRectForBounds:(CGRect)bounds trackRect:(CGRect)rect value:(float)value {
CGRect thumbRect = [super thumbRectForBounds:bounds trackRect:rect value:value];
lastKnownThumbRect = thumbRect;
return thumbRect;
}
希望它可以帮助某人:)
我用过这段代码。获取自:http: //imagineric.ericd.net/2012/11/15/uislider-touch-to-set-value/
UITapGestureRecognizer *gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(sliderTapped:)];
[slider addGestureRecognizer:gr];
- (void)sliderTapped:(UIGestureRecognizer *)g {
UISlider* s = (UISlider*)g.view;
if (s.highlighted)
return; // tap on thumb, let slider deal with it
CGPoint pt = [g locationInView: s];
CGFloat percentage = pt.x / s.bounds.size.width;
CGFloat delta = percentage * (s.maximumValue - s.minimumValue);
CGFloat value = s.minimumValue + delta;
[s setValue:value animated:YES];
}
希望这可以帮到你。