NSScrollView有時有一個黑色條而不是滾動條

Question

在我的基於OS X應用程序的文檔中，我在xib中有一個空的NSScrollView，並設置了「顯示垂直滾動條」。在運行時，我用導航按鈕生成一個視圖，將其設置爲NSScrollView的文檔視圖。大多數情況下，這種方式效果不錯，但大約有25％的時間，似乎是隨機的（或者至少我不能再現任何特定的情況！），而不是側面的滾動條，我會在黑色的酒吧滾輪應該是。如果我調整窗口大小，黑色條消失，滾動條出現並且工作正常。

結果是，如果我一個接一個地打開六個或七個空白文檔，其中大約三個不會立即運行滾動視圖。

下面是使用導航按鈕創建視圖並將其添加爲NSScrollview的documentView的代碼。

YMScrollDocView是NSView的一個子類，它將isFlipped設置爲YES。 navScrollView是xib中滾動視圖的出口。

float allHeight = 0.f; // Consider starting from the top 
//float xOffset = 2.f; // Offset addjustments 
float spacing = 4.f; // Spacing 
float buttonCellHeight = 40.f; 

YMScrollDocView *navView = [[YMScrollDocView alloc]init]; 

//1 
NSButton *overviewButton = [[NSButton alloc]initWithFrame:NSMakeRect(0, allHeight, self.navScrollView.bounds.size.width, buttonCellHeight)]; 

[overviewButton setTitle:@"Overview"]; 
[overviewButton setButtonType:NSMomentaryLight]; 
[overviewButton setBordered:NO]; 
[[overviewButton cell]setBackgroundColor:[self colorWithHexColorString:@"30BDF8"]]; 
[overviewButton setBezelStyle:NSRegularSquareBezelStyle]; 
[overviewButton setButtonType:NSCellIsBordered]; 
[overviewButton setTarget:self]; 
[overviewButton setAction:@selector(goToOverview)]; 
[overviewButton setRefusesFirstResponder:YES]; 
[navView addSubview:overviewButton]; 
allHeight += buttonCellHeight; 
allHeight += spacing; 


//2 
NSButton *curriculumButton = [[NSButton alloc]initWithFrame:NSMakeRect(0, allHeight, self.navScrollView.bounds.size.width, buttonCellHeight)]; 

[curriculumButton setTitle:@"Curriculum"]; 
[curriculumButton setButtonType:NSMomentaryLight]; 
[curriculumButton setBordered:NO]; 
[[curriculumButton cell]setBackgroundColor:[self colorWithHexColorString:@"36FBF8"]]; 
[curriculumButton setBezelStyle:NSRegularSquareBezelStyle]; 
[curriculumButton setButtonType:NSCellIsBordered]; 
[curriculumButton setTarget:self]; 
[curriculumButton setAction:@selector(goToCurriculum)]; 
[curriculumButton setRefusesFirstResponder:YES]; 
[navView addSubview:curriculumButton]; 
allHeight += buttonCellHeight; 
allHeight += spacing; 

（我添加更多按鈕與重複的代碼在這裏，然後用下面的代碼完成。）

[navView setFrame:NSMakeRect(1, 1, self.navScrollView.bounds.size.width, allHeight)]; 
[[self navScrollView]setDocumentView:navView]; 

Answer 1

我跑你的代碼（略作修改，以看到滾動條）。您在Interface Builder中爲NSScrollView設置了哪些屬性？另外你在哪裏設置文檔視圖等？（你的上面的代碼）。我在NSDocument的下面的方法中初始化了它們，並且它一切正常！

- (void)windowControllerDidLoadNib:(NSWindowController *)aController 
{ 
    [super windowControllerDidLoadNib:aController]; 

    float allHeight = 0.f; // Consider starting from the top 
    float spacing = 4.f; // Spacing 
    float buttonCellHeight = 4000.f; 

    CustomView *navView = [[CustomView alloc]init]; 
    //1 
    NSButton *overviewButton = [[NSButton alloc]initWithFrame:NSMakeRect(0, allHeight, _scrollView.bounds.size.width, buttonCellHeight)]; 

    // Setup overviewButton properties 
    [navView addSubview:overviewButton]; 
    allHeight += buttonCellHeight; 
    allHeight += spacing; 

    //2 
    NSButton *curriculumButton = [[NSButton alloc]initWithFrame:NSMakeRect(0, allHeight, _scrollView.bounds.size.width, buttonCellHeight)]; 

    // setup curriculumButton properties 
    [navView addSubview:curriculumButton]; 
    allHeight += buttonCellHeight; 
    allHeight += spacing; 

    [navView setFrame:NSMakeRect(1, 1, _scrollView.bounds.size.width, allHeight)]; 
    [_scrollView setDocumentView:navView]; 
} 

Answer 2

我還沒有完全解決這個問題，但我想出了一個我認爲我會分享的hacky解決方案。現在，我正在調用一個單獨的方法在啓動後立即調整窗口大小。這是在windowControllerDidLoadNib結束：

[self performSelector: @selector(resizeWidth) withObject: nil afterDelay:0.0f]; 

這就要求：

-(void)resizeWidth 
{ 
NSRect newFrame = NSMakeRect(oldFrame.origin.x, oldFrame.origin.y, 975, oldFrame.size.height); 
[[self docWindow]setFrame:newFrame display:YES animate:YES]; 
} 

我不喜歡這個解決方案，特別是因爲它創造了一個非常小的動畫吸引了用戶的眼球，但它是非常快速，往往不明顯，總是比原始問題少侵入。至少通過這種方式，應用程序的滾動器可以立即提供給用戶，而UI的功能無需用戶調整窗口大小。