iOS彩虹色数组

Question

我正在设置一个数组，该数组在整个彩虹色之间都有过渡。现在我只是在数组中手动​​输入了颜色，但是手动输入的颜色太多了……到目前为止，我只是从0.25到0.5到0.75到1等等，直到从红色变成绿色再变成蓝色为止然后回来。 （请参阅下面的代码）我如何让数组自动生成超过0.25-> 0.5-> 0.75但可能是0.05-> 0.10-> 0.15-> 0.20等的颜色，依此类推，...这是我的数组：

rainbowColors = [[NSArray alloc] initWithObjects:
                     [UIColor colorWithRed:1 green:0 blue:0 alpha:1],
                     [UIColor colorWithRed:1 green:0.25 blue:0 alpha:1],
                     [UIColor colorWithRed:1 green:0.5 blue:0 alpha:1],
                     [UIColor colorWithRed:1 green:0.75 blue:0 alpha:1],
                     [UIColor colorWithRed:1 green:1 blue:0 alpha:1],
                     [UIColor colorWithRed:0.75 green:1 blue:0 alpha:1],
                     [UIColor colorWithRed:0.5 green:1 blue:0 alpha:1],
                     [UIColor colorWithRed:0.25 green:1 blue:0 alpha:1],
                     [UIColor colorWithRed:0 green:1 blue:0 alpha:1],
                     [UIColor colorWithRed:0 green:1 blue:0.25 alpha:1],
                     [UIColor colorWithRed:0 green:1 blue:0.5 alpha:1],
                     [UIColor colorWithRed:0 green:1 blue:0.75 alpha:1],
                     [UIColor colorWithRed:0 green:1 blue:1 alpha:1],
                     [UIColor colorWithRed:0 green:0.75 blue:1 alpha:1],
                     [UIColor colorWithRed:0 green:0.5 blue:1 alpha:1],
                     [UIColor colorWithRed:0 green:0.25 blue:1 alpha:1],
                     [UIColor colorWithRed:0 green:0 blue:1 alpha:1],
                     [UIColor colorWithRed:0.25 green:0 blue:1 alpha:1],
                     [UIColor colorWithRed:0.5 green:0 blue:1 alpha:1],
                     [UIColor colorWithRed:0.75 green:0 blue:1 alpha:1],
                     [UIColor colorWithRed:1 green:0 blue:1 alpha:1],
                     [UIColor colorWithRed:1 green:0 blue:0.75 alpha:1],
                     [UIColor colorWithRed:1 green:0 blue:0.5 alpha:1],
                     [UIColor colorWithRed:1 green:0 blue:0.25 alpha:1],nil];

Answer 1

更简单，使用-[UIColor colorWithHue:saturation:brightness:alpha:]，如下所示：

NSMutableArray *colors = [NSMutableArray array];

float INCREMENT = 0.05;
for (float hue = 0.0; hue < 1.0; hue += INCREMENT) {
    UIColor *color = [UIColor colorWithHue:hue
                                saturation:1.0
                                brightness:1.0
                                     alpha:1.0];
    [colors addObject:color];
}

这可以让您改变色调（或颜色），而无需更改屏幕上颜色的明亮程度，您现在很可能无法保留这种颜色。编写起来也容易得多，对以后的读者也更清楚。

Answer 2

3个嵌套的循环和3个变量r，g，b，每次循环发生时加0.25。

Answer 3

[Swift 5，iOS 13更新为BJHomer答案

extension UIButton {
  func rainbowText() {
    var colors:[UIColor] = []
    let increment:CGFloat = 0.02
    for hue:CGFloat in stride(from: 0.0, to: 1.0, by: increment) {
      let color = UIColor(hue: hue, saturation: 1.0, brightness: 1.0, alpha: 1.0)
      colors.append(color)
    }
    var colorIndex = 0
    Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { (timer) in
      if colorIndex < colors.count {
        self.setTitleColor(colors[colorIndex], for: .normal)
        colorIndex = colorIndex + 1
      } else {
        self.setTitleColor(colors[0], for: .normal)
        timer.invalidate()
      }
    }
  }
}

您这样称呼它...

buttonOutlet.rainbowText()