使用 CGWindowListCopyWindowInfo 最前面的窗口

在文档中，它说此方法返回的窗口列表：

CFArrayRef windowList = CGWindowListCopyWindowInfo(kCGWindowListOptionOnScreenOnly, kCGNullWindowID);

将按从前到后的顺序返回窗口。但事实并非如此……最前面的窗口应该是测试的，但这是这个数组的结果：

2011-03-12 18:18:14.221 test[982:a0f] (
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 22;
            Width = 212;
            X = 1662;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 25;
        kCGWindowMemoryUsage = 30104;
        kCGWindowName = "";
        kCGWindowNumber = 14;
        kCGWindowOwnerName = SystemUIServer;
        kCGWindowOwnerPID = 99;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 0;
        kCGWindowBounds =         {
            Height = 22;
            Width = 1920;
            X = 0;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 25;
        kCGWindowMemoryUsage = 5528;
        kCGWindowNumber = 15;
        kCGWindowOwnerName = SystemUIServer;
        kCGWindowOwnerPID = 99;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 22;
            Width = 46;
            X = 1874;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 25;
        kCGWindowMemoryUsage = 5528;
        kCGWindowName = "";
        kCGWindowNumber = 12;
        kCGWindowOwnerName = SystemUIServer;
        kCGWindowOwnerPID = 99;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 22;
            Width = 1920;
            X = 0;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 24;
        kCGWindowMemoryUsage = 218520;
        kCGWindowName = "Shared Menubar";
        kCGWindowNumber = 6;
        kCGWindowOwnerName = "Window Server";
        kCGWindowOwnerPID = 73;
        kCGWindowSharingState = 2;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 1058;
            Width = 1920;
            X = 0;
            Y = 22;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 20;
        kCGWindowMemoryUsage = 1200;
        kCGWindowNumber = 13;
        kCGWindowOwnerName = Dock;
        kCGWindowOwnerPID = 98;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 52;
            Width = 676;
            X = 622;
            Y = 1028;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 19;
        kCGWindowMemoryUsage = 157080;
        kCGWindowName = "Magic Mirror";
        kCGWindowNumber = 16;
        kCGWindowOwnerName = Dock;
        kCGWindowOwnerPID = 98;
        kCGWindowSharingState = 2;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 382;
            Width = 480;
            X = 335;
            Y = 367;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 792496;
        kCGWindowName = test;
        kCGWindowNumber = 252;
        kCGWindowOwnerName = test;
        kCGWindowOwnerPID = 982;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 807;
            Width = 1206;
            X = 321;
            Y = 157;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 4055280;
        kCGWindowName = "AppDelegate.m - test";
        kCGWindowNumber = 24;
        kCGWindowOwnerName = Xcode;
        kCGWindowOwnerPID = 132;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 967;
            Width = 960;
            X = 175;
            Y = 22;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 3817968;
        kCGWindowName = "test - Debugger Console";
        kCGWindowNumber = 31;
        kCGWindowOwnerName = Xcode;
        kCGWindowOwnerPID = 132;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 967;
            Width = 1845;
            X = 121;
            Y = 22;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 882288;
        kCGWindowName = "CocoaDev Forums - get focused window id";
        kCGWindowNumber = 80;
        kCGWindowOwnerName = "Google Chrome";
        kCGWindowOwnerPID = 244;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 784;
            Width = 885;
            X = 560;
            Y = 157;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 318768;
        kCGWindowName = "Console Messages";
        kCGWindowNumber = 125;
        kCGWindowOwnerName = Console;
        kCGWindowOwnerPID = 482;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 494;
            Width = 1167;
            X = 519;
            Y = 417;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 2441264;
        kCGWindowName = Debug;
        kCGWindowNumber = 54;
        kCGWindowOwnerName = Finder;
        kCGWindowOwnerPID = 100;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 382;
            Width = 480;
            X = 335;
            Y = 367;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 55216;
        kCGWindowName = test;
        kCGWindowNumber = 223;
        kCGWindowOwnerName = test;
        kCGWindowOwnerPID = 849;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 437;
            Width = 770;
            X = 396;
            Y = 308;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 238512;
        kCGWindowName = Applications;
        kCGWindowNumber = 19;
        kCGWindowOwnerName = Finder;
        kCGWindowOwnerPID = 100;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 437;
            Width = 770;
            X = 450;
            Y = 429;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = 0;
        kCGWindowMemoryUsage = 332720;
        kCGWindowName = Applications;
        kCGWindowNumber = 17;
        kCGWindowOwnerName = Finder;
        kCGWindowOwnerPID = 100;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
        kCGWindowWorkspace = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 14;
            Width = 1920;
            X = 0;
            Y = 22;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = "-20";
        kCGWindowMemoryUsage = 5528;
        kCGWindowName = "Backstop Menubar";
        kCGWindowNumber = 11;
        kCGWindowOwnerName = "Window Server";
        kCGWindowOwnerPID = 73;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 2;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 1080;
            Width = 1920;
            X = 0;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = "-2147483627";
        kCGWindowMemoryUsage = 1200;
        kCGWindowName = "";
        kCGWindowNumber = 10;
        kCGWindowOwnerName = Finder;
        kCGWindowOwnerPID = 100;
        kCGWindowSharingState = 1;
        kCGWindowStoreType = 1;
    },
        {
        kCGWindowAlpha = 1;
        kCGWindowBounds =         {
            Height = 1080;
            Width = 1920;
            X = 0;
            Y = 0;
        };
        kCGWindowIsOnscreen = 1;
        kCGWindowLayer = "-2147483628";
        kCGWindowMemoryUsage = 8328600;
        kCGWindowName = Desktop;
        kCGWindowNumber = 2;
        kCGWindowOwnerName = "Window Server";
        kCGWindowOwnerPID = 73;
        kCGWindowSharingState = 2;
        kCGWindowStoreType = 2;
    }
)

SystemUIServer、dock、魔镜是什么？这些不是我最喜欢的应用程序。谢谢！

获取 Apple 示例应用程序的副本：抢夺之子 http://developer.apple.com/library/mac/#samplecode/SonOfGrab/Introduction/Intro.html。然后构建并运行它，您将拥有一个非常方便的交互式应用程序，用于调查窗口服务器已知的所有窗口。

您的问题的答案是窗口是从前到后排序的，但是定义为窗口的用户界面元素比您预期的要多得多。这包括菜单栏、停靠栏、服务菜单、桌面等。这些是在不同级别定义的，对应于kCGWindowLayer在你的输出中。

您希望在标准窗口级别（零）定义第一个窗口。如果你看一下你的输出，第一个窗口kCGWindowLayer == 0事实上是第七个。