Xcode的代码编辑器是可以进行主题设置的，如果是白色背景一般会比较伤眼，所以都会修改一些主题。
在Xcode菜单栏中进行偏好设置，可以设置Fonts&Colors，它会提供一些现有的主题，可以对现有的主题进行颜色、字体大小的设置：
image
也可以自行进行设置，或者下载其他人设置好的主题文件，导入到Xcode中去。比如我这个主题：
image
主题文件都是xml写的，内容在文末可以直接复制，新建一个文件命名为Monokai.dvtcolortheme，将文末的xml内容复制进去就可以了。
然后将这个主题文件放到Xcode的主题文件夹中，这个文件夹通过终端来打开比较方便，路径是：~/Library/Developer/Xcode/UserData/FontAndColorThemes/
放进去后重启一下Xcode，就可以在偏好设置中看到他了，选中就可以了，我习惯将所有文字大小都调成18，比较大，看起来对眼睛好一些，也可以把背景调成护眼色（色调：55，饱和度：123，亮度：205，红：199，绿：237，蓝：204）。
主题内容：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>DVTConsoleDebuggerInputTextColor</key>
<string>0.973 0.973 0.941 1</string>
<key>DVTConsoleDebuggerInputTextFont</key>
<string>Menlo-Regular - 12.0</string>
<key>DVTConsoleDebuggerOutputTextColor</key>
<string>0.973 0.973 0.941 1</string>
<key>DVTConsoleDebuggerOutputTextFont</key>
<string>Menlo-Regular - 12.0</string>
<key>DVTConsoleDebuggerPromptTextColor</key>
<string>0.973 0.973 0.949 1</string>
<key>DVTConsoleDebuggerPromptTextFont</key>
<string>Menlo-Regular - 12.0</string>
<key>DVTConsoleExectuableInputTextColor</key>
<string>0.973 0.973 0.941 1</string>
<key>DVTConsoleExectuableInputTextFont</key>
<string>Menlo-Regular - 12.0</string>
<key>DVTConsoleExectuableOutputTextColor</key>
<string>0.973 0.973 0.949 1</string>
<key>DVTConsoleExectuableOutputTextFont</key>
<string>Menlo-Regular - 12.0</string>
<key>DVTConsoleTextBackgroundColor</key>
<string>0.153 0.157 0.133 1</string>
<key>DVTConsoleTextInsertionPointColor</key>
<string>0.973 0.973 0.941 1</string>
<key>DVTConsoleTextSelectionColor</key>
<string>0.219608 0.219608 0.188235 1</string>
<key>DVTDebuggerInstructionPointerColor</key>
<string>0.705792 0.8 0.544 1</string>
<key>DVTSourceTextBackground</key>
<string>0.153 0.157 0.133 1</string>
<key>DVTSourceTextBlockDimBackgroundColor</key>
<string>0.153 0.157 0.133 1</string>
<key>DVTSourceTextInsertionPointColor</key>
<string>0.973 0.973 0.941 1</string>
<key>DVTSourceTextInvisiblesColor</key>
<string>0.153 0.157 0.133 1</string>
<key>DVTSourceTextSelectionColor</key>
<string>0.219608 0.219608 0.188235 1</string>
<key>DVTSourceTextSyntaxColors</key>
<dict>
<key>xcode.syntax.attribute</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.character</key>
<string>0.682 0.506 1 1</string>
<key>xcode.syntax.comment</key>
<string>0.459 0.443 0.369 1</string>
<key>xcode.syntax.comment.doc</key>
<string>0.459 0.443 0.369 1</string>
<key>xcode.syntax.comment.doc.keyword</key>
<string>0.459 0.443 0.369 1</string>
<key>xcode.syntax.identifier.class</key>
<string>0.651 0.886 0.18 1</string>
<key>xcode.syntax.identifier.class.system</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.identifier.constant</key>
<string>0.651 0.886 0.18 1</string>
<key>xcode.syntax.identifier.constant.system</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.identifier.function</key>
<string>0.651 0.886 0.18 1</string>
<key>xcode.syntax.identifier.function.system</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.identifier.macro</key>
<string>0.992 0.592 0.122 1</string>
<key>xcode.syntax.identifier.macro.system</key>
<string>0.992 0.592 0.122 1</string>
<key>xcode.syntax.identifier.type</key>
<string>0.651 0.886 0.18 1</string>
<key>xcode.syntax.identifier.type.system</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.identifier.variable</key>
<string>0.651 0.886 0.18 1</string>
<key>xcode.syntax.identifier.variable.system</key>
<string>0.4 0.851 0.937 1</string>
<key>xcode.syntax.keyword</key>
<string>0.976 0.149 0.447 1</string>
<key>xcode.syntax.number</key>
<string>0.682 0.506 1 1</string>
<key>xcode.syntax.plain</key>
<string>0.973 0.973 0.949 1</string>
<key>xcode.syntax.preprocessor</key>
<string>0.976 0.149 0.447 1</string>
<key>xcode.syntax.string</key>
<string>0.902 0.859 0.455 1</string>
<key>xcode.syntax.url</key>
<string>0.459 0.443 0.369 1</string>
</dict>
<key>DVTSourceTextSyntaxFonts</key>
<dict>
<key>xcode.syntax.attribute</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.character</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.comment</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.comment.doc</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.comment.doc.keyword</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.class</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.class.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.constant</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.constant.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.function</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.function.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.macro</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.macro.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.type</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.type.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.variable</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.identifier.variable.system</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.keyword</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.number</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.plain</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.preprocessor</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.string</key>
<string>Menlo-Regular - 12.0</string>
<key>xcode.syntax.url</key>
<string>Menlo-Regular - 12.0</string>
</dict>
</dict>
</plist>
