ios UITabBarItem 图片大小
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UITabBarItem Image Size
提问by user2397282
I am making images for my UITabBar. I am making them of size 60x60, because that's what retina screens use. However, when I use that size, it shows up too big in the bar, so you can only see part of the image. When I reduce it down to 30x30, it works, but that size is supposed to be for non-retina displays. Why does it not show up properly when I use 60x60?
我正在为我的 UITabBar 制作图像。我正在制作 60x60 的尺寸，因为这是视网膜屏幕使用的。但是，当我使用该尺寸时，它在栏中显示太大，因此您只能看到图像的一部分。当我将其缩小到 30x30 时，它可以工作，但该尺寸应该用于非视网膜显示器。为什么当我使用 60x60 时它不能正确显示？
回答by thatzprem
You probably may have to rename your retina image to [email protected].
您可能需要将您的视网膜图像重命名为[email protected].
回答by radiovisual
You were getting this behavior because you were supplying a high-resolution image, when iOS was looking for a standard resolution image.
您之所以出现这种行为，是因为当 iOS 正在寻找标准分辨率图像时，您提供的是高分辨率图像。
iOS automatically selects the appropriate image size for you, depending on the resolution of the accessing device. So you will be responsible for supplying a "standard resolution" image, for non-retina devices, and a "high resolution" image, for retina displays. The way you do this in iOS is to append "@2x" to the end of your filename, but before the file extension, like this:
iOS 会自动为您选择合适的图像大小，具体取决于访问设备的分辨率。因此，您将负责为非视网膜设备提供“标准分辨率”图像，以及为视网膜显示器提供“高分辨率”图像。在 iOS 中执行此操作的方法是将“@2x”附加到文件名的末尾，但在文件扩展名之前，如下所示：
my-image.png // for non-retina displays (Ex: 30x30 dpi)
[email protected] // for retina displays (Ex: 60x60 dpi)
[email protected] // for retina displays(plus editions) (Ex: 90x90 dpi)
Then, when you are referencing files in your XCode project, you only need to supply the filename to the standard resolution (e.g, "my-image.png") and if the accessing device has a retina display, then XCode will automatically select the file with the "@2x" suffix for you.This is very convenient, because it saves us developers from having to detect whether or not the device has a retina display, and which image we need to supply.
然后，当你在你的 XCode 项目中引用文件时，你只需要提供标准分辨率的文件名（例如，“my-image.png”），如果访问设备有视网膜显示，那么XCode 将自动选择为您创建带有“@2x”后缀的文件。这非常方便，因为它使我们开发人员不必检测设备是否具有视网膜显示屏，以及我们需要提供哪些图像。
Here is a code example:
这是一个代码示例：
// Select an image named "my-image.png"
UIImage *img = [UIImage imageNamed:@"my-image.png"];
// If the device this code is run on is a retina device,
// then Xcode will automatically search for "[email protected]" and "[email protected]"
// otherwise, it will use "my-image.png"
You can read more on the subject via the Apple Developer's Site: Optimizing for High Resolution
您可以通过 Apple Developer's Site: Optimizing for High Resolution阅读有关该主题的更多信息
