blocks|key|299729|text|我不确定你是否在寻找某种Objective-C的答案，但基于RGBA指定的颜色如何工作，我认为你可以简单地根据任意因子缩放RGB值，以获得“较亮”或“较暗”的阴影。例如，您可能有一个蓝色：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|299730|[UIColor+colorWithRed:0.0+green:0.0+blue:1.0+alpha:1.0];|code-block|syntax|javascript|299731|想要深蓝色的吗？将RGB值乘以0.9：|299732|[UIColor+colorWithRed:0.0+green:0.0+blue:0.9+alpha:1.0];|299733|瞧。或者你有一个桔子：|299734|[UIColor+colorWithRed:1.0+green:0.4+blue:0.0+alpha:1.0];|299735|选择另一个比例因子，例如0.8：|299736|[UIColor+colorWithRed:0.8+green:0.32+blue:0.0+alpha:1.0];|299737|这就是你想要的效果吗？|299738|entityMap^0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|12|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|14|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|15|8|@]|9|@]|A|$]]]|V|$]]

I'm not sure if you're looking for some sort of Objective-C answer, but based on how colors specified by RGBA work, I think you can simply scale the RGB values according to an arbitrary factor to get a "lighter" or "darker" shade. For example, you might have a blue:

<pre><code>[UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];
</code></pre>

Want a darker blue? Multiply the RGB values by 0.9:

<pre><code>[UIColor colorWithRed:0.0 green:0.0 blue:0.9 alpha:1.0];
</code></pre>

Voila. Or maybe you have an orange:

<pre><code>[UIColor colorWithRed:1.0 green:0.4 blue:0.0 alpha:1.0];
</code></pre>

Choose another scale factor, say, 0.8:

<pre><code>[UIColor colorWithRed:0.8 green:0.32 blue:0.0 alpha:1.0];
</code></pre>

Is that the sort of effect you're looking for?

blocks|key|516398|text|如果将RGB颜色转化为HSL+color+model，则可以将L=亮度分量从L=+0.0+(黑色)从L=+0.5+(自然色)更改为L=+1.0+(白色)。UIColor不能直接处理HSL，但有转换RGB<->+HSL的公式。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|516399|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/HSL_and_HSV^0|25|7|B|F|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]]|D|@$9|Q|A|R|1|S]]|E|$]]|$1|F|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|G|$H|$5|I|J|K|E|$L|M]]]]

If you convert the RGB color to the <a href="http://en.wikipedia.org/wiki/HSL_and_HSV">HSL color model</a> then you can vary the L = lightness component from L = 0.0 (black) over L = 0.5 (natural color) to L = 1.0 (white) . <code>UIColor</code> cannot handle HSL directly, but there are formula for converting RGB &lt;-> HSL.

blocks|key|299886|text|如果你想让user529758的解决方案使用灰色阴影(如[UIColor+lightGrayColor]或[UIColor+darkGrayColor]+)，你必须像这样改进它：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|299887|-+(UIColor+*)lighterColor
{
++++CGFloat+h,+s,+b,+a;
++++if+([self+getHue:&h+saturation:&s+brightness:&b+alpha:&a])+{
++++++++return+[UIColor+colorWithHue:h
++++++++++++++++++++++++++saturation:s
++++++++++++++++++++++++++brightness:MIN(b+*+1.3,+1.0)
+++++++++++++++++++++++++++++++alpha:a];
++++}

++++CGFloat+white,+alpha;
++++if+([self+getWhite:&white+alpha:&alpha])+{
++++++++white+=+MIN(1.3*white,+1.0);
++++++++return+[UIColor+colorWithWhite:white+alpha:alpha];
++++}

++++return+nil;
}|code-block|syntax|javascript|299888|在灰色阴影上调用时，getHue:saturation:brightness:alpha会失败(并返回false)，因此您需要使用getWhite:alpha。|299889|entityMap^0|S|O|1H|N|0|0|A|Y|1F|5|1T|E|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|N|$]]

If you want user529758's solution to work with gray shades (like <code>[UIColor lightGrayColor]</code> or <code>[UIColor darkGrayColor]</code> you have to improve it like that: 

<pre><code>- (UIColor *)lighterColor
{
 CGFloat h, s, b, a;
 if ([self getHue:&amp;h saturation:&amp;s brightness:&amp;b alpha:&amp;a]) {
 return [UIColor colorWithHue:h
 saturation:s
 brightness:MIN(b * 1.3, 1.0)
 alpha:a];
 }

 CGFloat white, alpha;
 if ([self getWhite:&amp;white alpha:&amp;alpha]) {
 white = MIN(1.3*white, 1.0);
 return [UIColor colorWithWhite:white alpha:alpha];
 }

 return nil;
}
</code></pre>

<code>getHue:saturation:brightness:alpha</code> fails (and returns <code>false</code>) when called on a gray shade therefore you'll need to use <code>getWhite:alpha</code>.

blocks|key|299946|text|UIColor扩展和修复lighterColorForColor|type|unstyled|depth|inlineStyleRanges|entityRanges|data|299947|extension+UIColor+{
++class+func+darkerColorForColor(color:+UIColor)+->+UIColor+{
++++var+r:CGFloat+=+0,+g:CGFloat+=+0,+b:CGFloat+=+0,+a:CGFloat+=+0
++++if+color.getRed(&r,+green:+&g,+blue:+&b,+alpha:+&a){
++++++return+UIColor(red:+max(r+-+0.2,+0.0),+green:+max(g+-+0.2,+0.0),+blue:+max(b+-+0.2,+0.0),+alpha:+a)
++++}
++++return+UIColor()
++}

++class+func+lighterColorForColor(color:+UIColor)+->+UIColor+{
++++var+r:CGFloat+=+0,+g:CGFloat+=+0,+b:CGFloat+=+0,+a:CGFloat+=+0
++++if+color.getRed(&r,+green:+&g,+blue:+&b,+alpha:+&a){
++++++let+tmpColor+=+UIColor(red:+min(r+%2B+0.2,+1.0),+green:+min(g+%2B+0.2,+1.0),+blue:+min(b+%2B+0.2,+1.0),+alpha:+a)
++++++println(tmpColor)
++++++return+tmpColor
++++}
++++return+UIColor()
++}
}|code-block|syntax|javascript|299948|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

UIColor extension and fixing lighterColorForColor

<pre><code>extension UIColor {
 class func darkerColorForColor(color: UIColor) -&gt; UIColor {
 var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
 if color.getRed(&amp;r, green: &amp;g, blue: &amp;b, alpha: &amp;a){
 return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
 }
 return UIColor()
 }

 class func lighterColorForColor(color: UIColor) -&gt; UIColor {
 var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
 if color.getRed(&amp;r, green: &amp;g, blue: &amp;b, alpha: &amp;a){
 let tmpColor = UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
 println(tmpColor)
 return tmpColor
 }
 return UIColor()
 }
}
</code></pre>

blocks|key|516555|text|理想情况下，这些函数应该封装在一个名为UIColor%2BBrightness.swift的UIColor扩展中，并具有可配置的亮度-请参见以下示例：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|516556|import+UIKit

extension+UIColor+{

++func+lighterColorWithBrightnessFactor(brightnessFactor:CGFloat)+->+UIColor+{
++++var+r:CGFloat+=+0,+g:CGFloat+=+0,+b:CGFloat+=+0,+a:CGFloat+=+0
++++if+self.getRed(&r,+green:&g,+blue:&b,+alpha:&a)+{
++++++return+UIColor(red:min(r+%2B+brightnessFactor,+1.0),
++++++++green:min(g+%2B+brightnessFactor,+1.0),
++++++++blue:min(b+%2B+brightnessFactor,+1.0),
++++++++alpha:a)
++++}
++++return+UIColor()
++}

}|code-block|syntax|javascript|516557|entityMap^0|J|O|18|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

Ideally, the functions should be encapsulated inside a <code>UIColor</code> extension called, <code>UIColor+Brightness.swift</code>, and have a configurable brightness - see example below:

<pre><code>import UIKit

extension UIColor {

 func lighterColorWithBrightnessFactor(brightnessFactor:CGFloat) -&gt; UIColor {
 var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
 if self.getRed(&amp;r, green:&amp;g, blue:&amp;b, alpha:&amp;a) {
 return UIColor(red:min(r + brightnessFactor, 1.0),
 green:min(g + brightnessFactor, 1.0),
 blue:min(b + brightnessFactor, 1.0),
 alpha:a)
 }
 return UIColor()
 }

}
</code></pre>

blocks|key|300063|text|我根据状态值呈现彩色单元格：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|300064|​|300065|📷|atomic|offset|length|300066|300067|为此，在使用CryingHippo的建议遇到错误后，我基于一些旧的objc代码编写了一个快速扩展：|300068|extension+UIColor{

++++func+darker(darker:+CGFloat)+->+UIColor{

++++++++var+red:+CGFloat+=+0.0
++++++++var+green:+CGFloat+=+0.0
++++++++var+blue:+CGFloat+=+0.0

++++++++if+self.colorSpace+==+UIColorSpace.genericGrayColorSpace(){

++++++++++++red+=++whiteComponent+-+darker
++++++++++++green+=+whiteComponent+-+darker
++++++++++++blue++=+whiteComponent+-+darker
++++++++}+else+{
++++++++++++red+=+redComponent+-+darker
++++++++++++green+=+greenComponent+-+darker
++++++++++++blue+=+blueComponent+-+darker
++++++++}

++++++++if+red+<+0{
++++++++++++green+%2B=+red/2
++++++++++++blue+%2B=+red/2
++++++++}

++++++++if+green+<+0{
++++++++++++red+%2B=+green/2
++++++++++++blue+%2B=+green/2
++++++++}

++++++++if+blue+<+0{
++++++++++++green+%2B=+blue/2
++++++++++++red+%2B=+blue/2
++++++++}

++++++++return+UIColor(
++++++++++++calibratedRed:+red,
++++++++++++green:+green,
++++++++++++blue:+blue,
++++++++++++alpha:+alphaComponent
++++++++)
++++}

++++func+lighter(lighter:+CGFloat)+->+UIColor{
++++++++return+darker(-lighter)
++++}
}|code-block|syntax|javascript|300069|同样的道理也适用于NSColor。只需用NSColor替换UIColor即可。|style|CODE|300070|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/9484a8ad7075cff81e5d3fe2dceea45b.png|imageAlt^0|0|0|0|1|0|0|0|0|0|9|7|K|7|T|7|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|14|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|15|8|@]|9|@$G|16|H|17|1|18]]|A|$]]|$1|I|3|C|5|6|7|19|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|1A|8|@]|9|@]|A|$]]|$1|L|3|M|5|N|7|1B|8|@]|9|@]|A|$O|P]]|$1|Q|3|R|5|6|7|1C|8|@$G|1D|H|1E|S|T]|$G|1F|H|1G|S|T]|$G|1H|H|1I|S|T]]|9|@]|A|$]]|$1|U|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11|12|-4]]]]

I render coloured cells based on a status value:

<img src="https://i.stack.imgur.com/NUXNW.png" alt="status-images">

For this I wrote a swift extension based on some old objc code after I got an error using CryingHippo's suggestion:

<pre><code>extension UIColor{

 func darker(darker: CGFloat) -&gt; UIColor{

 var red: CGFloat = 0.0
 var green: CGFloat = 0.0
 var blue: CGFloat = 0.0

 if self.colorSpace == UIColorSpace.genericGrayColorSpace(){

 red = whiteComponent - darker
 green = whiteComponent - darker
 blue = whiteComponent - darker
 } else {
 red = redComponent - darker
 green = greenComponent - darker
 blue = blueComponent - darker
 }

 if red &lt; 0{
 green += red/2
 blue += red/2
 }

 if green &lt; 0{
 red += green/2
 blue += green/2
 }

 if blue &lt; 0{
 green += blue/2
 red += blue/2
 }

 return UIColor(
 calibratedRed: red,
 green: green,
 blue: blue,
 alpha: alphaComponent
 )
 }

 func lighter(lighter: CGFloat) -&gt; UIColor{
 return darker(-lighter)
 }
}
</code></pre>

The same works for <code>NSColor</code> as well. Simply replace <code>UIColor</code> with <code>NSColor</code>.

blocks|key|516694|text|这是一个UIColor类别，它还允许控制颜色变化量。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|516695|-+(UIColor+*)lighterColorWithDelta:(CGFloat)delta
{
++++CGFloat+r,+g,+b,+a;
++++if+([self+getRed:&r+green:&g+blue:&b+alpha:&a])
++++++++return+[UIColor+colorWithRed:MIN(r+%2B+delta,+1.0)
+++++++++++++++++++++++++++++++green:MIN(g+%2B+delta,+1.0)
++++++++++++++++++++++++++++++++blue:MIN(b+%2B+delta,+1.0)
+++++++++++++++++++++++++++++++alpha:a];
++++return+nil;
}

-+(UIColor+*)darkerColorWithDelta:(CGFloat)delta
{
++++CGFloat+r,+g,+b,+a;
++++if+([self+getRed:&r+green:&g+blue:&b+alpha:&a])
++++++++return+[UIColor+colorWithRed:MAX(r+-+delta,+0.0)
+++++++++++++++++++++++++++++++green:MAX(g+-+delta,+0.0)
++++++++++++++++++++++++++++++++blue:MAX(b+-+delta,+0.0)
+++++++++++++++++++++++++++++++alpha:a];
++++return+nil;
}|code-block|syntax|javascript|516696|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here is a UIColor category that also allows control over the amount of color change.

<pre><code>- (UIColor *)lighterColorWithDelta:(CGFloat)delta
{
 CGFloat r, g, b, a;
 if ([self getRed:&amp;r green:&amp;g blue:&amp;b alpha:&amp;a])
 return [UIColor colorWithRed:MIN(r + delta, 1.0)
 green:MIN(g + delta, 1.0)
 blue:MIN(b + delta, 1.0)
 alpha:a];
 return nil;
}

- (UIColor *)darkerColorWithDelta:(CGFloat)delta
{
 CGFloat r, g, b, a;
 if ([self getRed:&amp;r green:&amp;g blue:&amp;b alpha:&amp;a])
 return [UIColor colorWithRed:MAX(r - delta, 0.0)
 green:MAX(g - delta, 0.0)
 blue:MAX(b - delta, 0.0)
 alpha:a];
 return nil;
}
</code></pre>

blocks|key|516726|text|对于较暗的颜色，这是最简单的:+theColor+=+theColor+shadowWithLevel:s；//s:0.0+to+1.0|type|unstyled|depth|inlineStyleRanges|entityRanges|data|516727|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

for darker color, this is the simplest:
 theColor = [theColor shadowWithLevel:s]; //s:0.0 to 1.0

I was looking to be able to turn any UIColor into a gradient. The way I am intending to do this is by using Core Graphics to draw a gradient. What I am trying to do is to get a color, lets say:

<pre><code>[UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];
</code></pre>

and get a UIColor which is a few shades darker and a few shades lighter. Does anyone know how to do this? Thank you.

Get Slightly Lighter and Darker Color from UIColor

Objective-C

我希望能够将任何UIColor转换为渐变。我打算这样做的方式是使用核心图形来绘制渐变。我想要做的是得到一个颜色，比方说：[UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];再买一台UIColor，它有几种色调较暗，一些色调较亮。有人知道怎么做吗？谢谢。

问从UIColor获得略微变亮和变暗的颜色
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