UISlider

UISlider

• 常用属性

1.@property(nonatomic) float value;                                 // default 0.0. this value will be pinned to min/max
2.@property(nonatomic) float minimumValue;                          // default 0.0. the current value may change if outside new min value
3.@property(nonatomic) float maximumValue;                          // default 1.0. the current value may change if outside new max value
4.@property(nullable, nonatomic,strong) UIColor *minimumTrackTintColor;
5.@property(nullable, nonatomic,strong) UIColor *maximumTrackTintColor;
6.@property(nullable, nonatomic,strong) UIColor *thumbTintColor

• 常用方法

1.- (void)setValue:(float)value animated:(BOOL)animated;
2.- (void)setThumbImage:(nullable UIImage *)image forState:(UIControlState)state;
3.- (void)setMinimumTrackImage:(nullable UIImage *)image forState:(UIControlState)state;
4.- (void)setMaximumTrackImage:(nullable UIImage *)image forState:(UIControlState)state;

• 注意： 设置trackImage时，需要对image作处理，官方文档是这么说的：The track images should be 3 part resizable (via UIImage’s resizableImage methods) along the direction that is longer

• 示例1

1.
2.- (void)viewDidLoad {
3.    [super viewDidLoad];
4.    // Do any additional setup after loading the view, typically from a nib.
5.
6.    self.view.backgroundColor = [UIColor colorWithRed:0.5 green:0.0 blue:1.0 alpha:1];
7.
8.
9.    UISlider *slider = [[UISlider alloc] initWithFrame:CGRectMake(0, 0, 300, 30)];
10.    slider.center = self.view.center;
11.
12.    slider.backgroundColor = [UIColor grayColor];
13.
14.    slider.minimumValue = 0;
15.
16.    slider.maximumValue = 1;
17.
18.    slider.minimumTrackTintColor = [UIColor greenColor];
19.
20.    slider.maximumTrackTintColor = [UIColor magentaColor];
21.
22.    slider.thumbTintColor = [UIColor cyanColor];
23.
24.    [self.view addSubview:slider];
25.
26.    [slider addTarget: self action:@selector(changeColor:) forControlEvents:UIControlEventValueChanged];
27.
28.}
29.
30.-(void)changeColor:(UISlider *)sender{
31.    self.view.backgroundColor = [UIColor colorWithRed:0.5 green:sender.value blue:1.0 alpha:1];
32.}

• 注：滑块大小不随frame的值改变而改变，如果设置了thumImage那么滑块的大小同image一样。当手触摸滑块的时候，滑块的状态为hightlighted

• 示例2（设置imgae）

  • 直接使用image

1.     [slider setThumbImage:[UIImage imageNamed:@"SliderThumb-Highlighted"] forState:UIControlStateHighlighted];
2.    [slider setThumbImage:[UIImage imageNamed:@"SliderThumb-Normal"] forState:UIControlStateNormal];
3.
4.    UIImage *leftImage = [UIImage imageNamed:@"SliderTrackLeft"];
5.    UIImage *rightImage = [UIImage imageNamed:@"SliderTrackRight"];
6.
7.    [slider setMinimumTrackImage:leftImage forState:UIControlStateNormal];
8.    [slider setMaximumTrackImage:rightImage forState:UIControlStateNormal]; 

可以看见，trackImage已经发生了形变，这绝对不是我们想要的效果。

• 对image进行处理一下

1.    leftImage = [leftImage resizableImageWithCapInsets:UIEdgeInsetsMake(0, 10, 0, 10)];
2.    rightImage = [rightImage resizableImageWithCapInsets:UIEdgeInsetsMake(0, 10, 0, 10)];