使用UIScreen驅動VGA顯示器 - 似乎不顯示UIWindow？

Question

HI there，

我試圖使用UIScreen在iPad上使用VGA加密狗驅動單獨的屏幕。

這裏就是我有我的根視圖控制器的viewDidLoad：

//Code to detect if an external display is connected to the iPad. 
NSLog(@"Number of screens: %d", [[UIScreen screens]count]); 

//Now, if there's an external screen, we need to find its modes, itereate through them and find the highest one. Once we have that mode, break out, and set the UIWindow. 

if([[UIScreen screens]count] > 1) //if there are more than 1 screens connected to the device 
{ 
    CGSize max; 
    UIScreenMode *maxScreenMode; 
    for(int i = 0; i < [[[[UIScreen screens] objectAtIndex:1] availableModes]count]; i++) 
    { 
    UIScreenMode *current = [[[[UIScreen screens]objectAtIndex:1]availableModes]objectAtIndex:i]; 
    if(current.size.width > max.width); 
    { 
    max = current.size; 
    maxScreenMode = current; 
    } 
    } 
    //Now we have the highest mode. Turn the external display to use that mode. 
    UIScreen *external = [[UIScreen screens] objectAtIndex:1]; 
    external.currentMode = maxScreenMode; 
    //Boom! Now the external display is set to the proper mode. We need to now set the screen of a new UIWindow to the external screen 
    external_disp = [externalDisplay alloc]; 
    external_disp.drawImage = drawViewController.drawImage; 
    UIWindow *newwindow = [UIWindow alloc]; 
    [newwindow addSubview:external_disp.view]; 
    newwindow.screen = external; 
} 

Answer 1

你需要初始化你的窗口...

UIWindow *newwindow = [[UIWindow alloc] init]; 

Answer 2

[newwindow makeKeyAndVisible];？

Answer 3

我覺得你的問題是externalDisplay。在你的代碼之外創建一個viewcontroller（也許做一個簡單的添加新文件ViewController並把東西放在.xib中），然後在將它調用到外部顯示之前確保viewcontroller正在工作。這是你的代碼和我的建議更改 - [mainViewController視圖]是您在外部創建的視圖控制器。

//Code to detect if an external display is connected to the iPad. 
NSLog(@"Number of screens: %d", [[UIScreen screens]count]); 

//Now, if there's an external screen, we need to find its modes, iterate 
//through them and find the highest one. Once we have that mode, break out, 
//and set the UIWindow. 

if([[UIScreen screens]count] > 1) //if there are more than 1 screens connected 
            //to the device 
{ 
CGSize max; 
UIScreenMode *maxScreenMode; 
for(int i = 0; i < [[[[UIScreen screens] objectAtIndex:1] availableModes]count]; i++) 
{ 
    UIScreenMode *current = [[[[UIScreen screens]objectAtIndex:1]availableModes]objectAtIndex:i]; 
    if(current.size.width > max.width); 
    { 
    max = current.size; 
    maxScreenMode = current; 
    } 
} 
//Now we have the highest mode. Turn the external display to use that mode. 
UIScreen *external = [[UIScreen screens] objectAtIndex:1]; 
external.currentMode = maxScreenMode; 
//Boom! Now the external display is set to the proper mode. We need to now 
//set the screen of a new UIWindow to the external screen 

UIWindow *newwindow = [UIWindow alloc]; 

[newwindow addSubview:[mainViewController view]]; 
newwindow.screen = external; 

[newwindow makeKeyAndVisible]; 
[newwindow setHidden:NO]; 
} 

Answer 4

我已經將示例.xcodeproj上傳到github中。

我主要是指這個頁面。

非常感謝。 :)

http://github.com/igaiga/iPadDisplayOutSample

Answer 5

它需要提及的是，提供了這個網頁上，並igaiga GitHub的鏈接代碼僅僅意味着「移動」（不能克隆），通常會在iPad上的觀點（或其他設備）。

如果您需要克隆（又名鏡像）的觀點，並刷新其內容這一環節更適合：http://www.touchcentric.com/blog/archives/123

我希望這有助於澄清這兩套代碼，爲用戶的使用情況剛剛開始整合將視頻輸出到現有應用程序中。

Answer 6

只是在這裏記錄這個以防止任何人在這個問題上絆倒。在我意識到我的應用程序委託必須保留UIWindow之前，我無法在第二個屏幕上顯示任何內容。它沒有自然的所有者，所以如果你只是做一個常規的autorelease，窗口會在它顯示之前被釋放。

希望有所幫助。