检测视网膜显示 [英] Detect Retina Display

问题描述

iOS SDK是否提供了一种简单的方法来检查currentDevice是否具有高分辨率显示器（视网膜）？

Does iOS SDK provides an easy way to check if the currentDevice has an high-resolution display (retina) ?

我发现这样做的最好方法现在是：

The best way I've found to do it now is :

    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] == YES && [[UIScreen mainScreen] scale] == 2.00) {
         // RETINA DISPLAY
    }

推荐答案

为了在所有iOS设备上可靠地检测Retina显示，您需要检查设备是否运行iOS4 +以及 [UIScreen mainScreen]。 scale property等于2.0。如果 scale 属性存在，则不能假设设备正在运行iOS4 +，因为iPad 3.2也包含此属性。

In order to detect the Retina display reliably on all iOS devices, you need to check if the device is running iOS4+ and if the [UIScreen mainScreen].scale property is equal to 2.0. You CANNOT assume a device is running iOS4+ if the scale property exists, as the iPad 3.2 also contains this property.

在运行iOS3.2的iPad上，刻度将在1x模式下返回1.0，在2x模式下返回2.0 - 即使我们知道该设备不包含Retina显示器。 Apple在iOS4.2中为iPad改变了这种行为：它在1x和2x模式下都返回1.0。你可以在模拟器中自己测试一下。

On an iPad running iOS3.2, scale will return 1.0 in 1x mode, and 2.0 in 2x mode -- even though we know that device does not contain a Retina display. Apple changed this behavior in iOS4.2 for the iPad: it returns 1.0 in both 1x and 2x modes. You can test this yourself in the simulator.

我测试主要的 -displayLinkWithTarget：selector：方法屏幕存在于iOS4.x而不是iOS3.2，然后检查屏幕的比例：

I test for the -displayLinkWithTarget:selector: method on the main screen which exists in iOS4.x but not iOS3.2, and then check the screen's scale:

if ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] &&
    ([UIScreen mainScreen].scale == 2.0)) {
  // Retina display
} else {
  // non-Retina display
}

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