uiview不会在app delegate中显示

Question

当我在模拟器中执行下面的代码时,我希望看到红色填满屏幕,但是它全是黑色,为什么？

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  UIView * myView = [[UIView alloc] initWithFrame:[window bounds]];
  [myView setBackgroundColor:[UIColor redColor]];
  [window addSubview:myView];
  [window makeKeyAndVisible];
  return YES;
}

如果我添加窗口的初始化,这没有帮助:

window = [[[UIWindow alloc] init] initWithFrame:[[UIScreen mainScreen] bounds]];

在Xcode中创建基于Window的Universal项目之后我开始麻烦了我决定删除iPad/iPhone xib文件和iPhone/iPad应用程序委托文件,这些文件是在项目中自动创建的,而是有一个带有视图的应用程序委托控制器,基于设备以编程方式构建视图.现在我似乎无法显示我在app delegate中创建的简单视图.

编辑:我删除了添加视图,现在将窗口的背景颜色设置为红色.这没有用,但如果我在模拟器中转到桌面并重新打开正在运行的应用程序,我现在得到一个红色屏幕.再一次,我很困惑,为什么我第一次启动应用程序时看不到红色.

Answer 1

以下是设置非InterfaceBuilder(.xib)通用iOS项目的步骤.

1. 删除应用程序属性列表中.xib文件的所有关联.

2. 从项目中删除所有.xib文件

3. (可选)创建一个公共Application Delegate类,然后删除AppDelegate_iPad.*和AppDelegate_iPhone.*文件.(在删除之前复制粘贴现有文件中的任何代码)

4. 更改main.m文件以命名应用程序委托.我选择修改并使用AppDelegate_iPhone作为示例.请参阅文档:UIApplication Reference

   // main.m int main(int argc,char*argv []){

   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
   // Start an iPhone/iPad App using a .xib file (Defaults set in .plist)
   //int retVal = UIApplicationMain(argc, argv, nil, nil);
   
   // Start the iPhone/iPad App programmatically
   // Set the 3rd argument to nil, to use the default UIApplication
   // Set the 4th argument to the string name of your AppDelegate class
   int retVal = UIApplicationMain(argc, argv, nil, @"AppDelegate_iPhone");
   
   [pool release];
   return retVal;
   

   }

5. 更新您的应用程序委托代码.

   // AppDelegate_iPhone.m - (BOOL)应用程序:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions {

       // Override point for customization after application launch.
       NSLog(@"Launch my application iphone");
   
       // Create the window, it's not created without a nib
       window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; 
   
       // Create a subview that is red
       UIView *myView = [[UIView alloc] initWithFrame:[window bounds]];
       [myView setBackgroundColor:[UIColor redColor]];
   
       // Add the subview and release the memory, sicne the window owns it now
       [self.window addSubview:myView];
       [myView release]; 
   
       [self.window makeKeyAndVisible];
   
       return YES;
   }