问题描述

从UISlider获取RGB颜色

改变UISLider的值使用方法：

@property (strong, nonatomic) IBOutlet UISlider *r;
@property (strong, nonatomic) IBOutlet UISlider *g;
@property (strong, nonatomic) IBOutlet UISlider *b;
@property (strong, nonatomic) IBOutlet UILabel *colorLabel;

- (void)viewDidLoad
{
    [super viewDidLoad];

    _r.minimumValue=0;
    _r.maximumValue=255;

    _g.minimumValue=0;
    _g.maximumValue=255;

    _b.minimumValue=0;
    _b.maximumValue=255;

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

-(void)sliderValueChanged:(UISlider*)slider
{
    [_colorLabel setBackgroundColor:[UIColor colorWithRed:_r.value green:_g.value blue:_b.value alpha:1]];
}

谢谢~

解决方案

设置颜色方法：

-(void)sliderValueChanged:(UISlider*)slider
{
    float r=[[NSString stringWithFormat:@"%.0f",_r.value] floatValue];
    float g=[[NSString stringWithFormat:@"%.0f",_g.value]floatValue];
    float b=[[NSString stringWithFormat:@"%.0f",_b.value]floatValue];

    UIColor *colorToSet=[UIColor colorWithRed:(r/255.0f) green:(g/255.0f) blue:(b/255.0f) alpha:1];
    [_colorLabel setBackgroundColor:colorToSet];
}

解决方案二：

你这个问题的关键在于：你在拿到UISlider的value后，使用[UIColor colorWithRed:green:blue:alpha:] 时并没有将得到各颜色的值除以255.0

UIColor *bgColor=[UIColor colorWithRed:_r.value/255.0f green:_g.value/255.0f blue:_b.value/255.0f alpha:1];
[_colorLabel setBackgroundColor:colorToSet];