Why doesn't setting the value property of this UISlider update its position?

问题

...ViewController.h:

@property (nonatomic, strong) IBOutlet UISlider *slider;

...ViewController.m:

@synthesize slider;

- (void)viewDidLoad
{
    [super viewDidLoad];

    ...
    currentValue = 50;
    self.slider.value = currentValue;

    // Do any additional setup after loading the view, typically from a nib.
}

.xib:

The UISlider in my interface is connected to the slider property.

Behavior:

The slider sits all the way to the right at value 100 when it is supposed to be in the middle. An action I set up confirms the value of currentValue is 50. If currentValue is 50 and slider.value is set to 50, why doesn't the position reflect this?

P.S. I tried [slider setNeedsDisplay] and it did not affect this behavior.

Update: thanks for the quick answers! What a silly thing to do. I print out currentValue as an int elsewhere so I am now setting slider.value with this code:

self.slider.value = (float) currentValue/100;

回答1:

currentValue = 50;

The slider's range is not 0...100 but 0...1. You have to write either

currentValue = 0.5;

or change the range of the slider:

self.slider.maximumValue = 100;

回答2:

Default range for UISlider is 0.0 to 1.0 (i.e. as a Float). Setting a value above max will cause the slider to show all the way to the right. Check your minimumValue and maximumValue properties.

来源：https://stackoverflow.com/questions/12322562/why-doesnt-setting-the-value-property-of-this-uislider-update-its-position