ios 有没有办法以编程方式调整屏幕亮度？
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Is there a way of adjusting the screen brightness programmatically?
提问by openfrog
I have an iPhone app for photographic purposes (kind of a lightbox). This app needs as much brightness as possible. Is there a way to change the screen brightness programmatically, and then restore it back some time later?
我有一个用于摄影的 iPhone 应用程序（有点像灯箱）。这个应用程序需要尽可能多的亮度。有没有办法以编程方式更改屏幕亮度，然后在一段时间后将其恢复？
回答by Alastair Stuart
Edit: iOS 5 now includes a screen brightness API.
编辑：iOS 5 现在包含一个屏幕亮度 API。
[[UIScreen mainScreen] setBrightness:0.5];
Previous answer:
上一个答案：
No, this capability is not exposed via public APIS.
不，此功能不会通过公共 APIS 公开。
Edit: Note that a future possible iOS release may or may not have screen brightness on the multitasking bar on one particular iDevice.
编辑：请注意，未来可能的 iOS 版本可能会或可能不会在一个特定 iDevice 上的多任务栏上显示屏幕亮度。
回答by Emil
It is possible, but your app will most likely get rejected from the App Store, because it uses a private API. A flashlight-app was rejected because it adjusted the screen brightness, so I wouldn't recommend it.
这是可能的，但您的应用很可能会被 App Store 拒绝，因为它使用私有 API。手电筒应用程序被拒绝，因为它调整了屏幕亮度，所以我不推荐它。
In iOS 4.2, the iPad will have a screen brightness-adjuster in the multitasking-bar,
在 iOS 4.2 中，iPad 的多任务栏中会有一个屏幕亮度调节器，
(as mentioned by @coob) so you could tell your users to set the brightness there.
（正如@coob 提到的）所以你可以告诉你的用户在那里设置亮度。
What you could do, is to create a black overlay-view, and set it's alpha to more or less, according to how bright you want the screen to be. This won't actually make the screen less/more bright, but it will give the user an illusion of that.
你可以做什么，是创建一个黑色的叠加图，它的alpha设置或多或少，根据你想如何亮屏幕是。这实际上不会使屏幕变暗/变亮，但会给用户一种错觉。
回答by Glenn Howes
Here's a Swift answer to this question.
这是对这个问题的 Swift 答案。
import UIKit
extension UIScreen
{
static func setMainBrightness(brightness: CGFloat)
{
guard (0...1).contains(brightness) else
{
print("Attempt to set the screen brightness to an invalid value: \(brightness) should be between 0 and 1 inclusive.")
return
}
self.main.brightness = brightness
}
}
Call it by using:
使用以下方法调用它：
UIScreen.setMainBrightness(0.5)
Or ignore my extension (which I just wrote to illustrate the limits) and just call:
或者忽略我的扩展（我只是为了说明限制而写的）并调用：
UIScreen.main.brightness = 0.5
