的UIScrollView和約束問題

Question

我創建一個UIScrollView：

// datasetSubView.m 
UIScrollView *scrollView = [UIScrollView new]; 
scrollView.translatesAutoresizingMaskIntoConstraints = FALSE; 
scrollView.userInteractionEnabled = TRUE; 
scrollView.scrollEnabled = TRUE; 
scrollView.backgroundColor = [UIColor whiteColor]; 
scrollView.alpha = 0; 

self.filterListView = scrollView; 

然後在我的UIViewController，我添加滾動視圖，並給它一個尺寸：

[self.view addSubview:self.datasetSubBar.filterListView]; 

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[filterListView]|" options:0 metrics:nil views:@{@"filterListView": self.datasetSubBar.filterListView}]]; 
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[filterListView][filtersSubBar]" options:0 metrics:nil views:@{@"filterListView": self.datasetSubBar.filterListView, @"filtersSubBar" : self.datasetSubBar.filtersSubBar}]]; 

[self.view layoutIfNeeded]; //gives the filterListView its frame 

我然後創建一個自定義的UIView到地方在滾動視圖中：

[self.datasetSubBar createPanels]; 

[self.datasetSubBar.filterListView layoutIfNeeded]; // w/out this, the panel's size is 0 

//datasetSubBar.m 
-(void)createPanels { 
    DatasetFilterListPanelView *panel = [[DatasetFilterListPanelView alloc] init]; 
    panel.translatesAutoresizingMaskIntoConstraints = FALSE; 
    panel.headerLabel.text = [NSString stringWithFormat:@"Panel %d", 1]; 
    panel.tag = 1; 

    [self.filterListView addSubview:panel]; 

    [self.filterListView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[panel]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(panel)]]; 
    [self.filterListView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:[panel]-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(panel)]]; 

    self.panels = @[panel]; 
} 

它應該將subView放置在右上角，但它不會：

NSLog(@"viewDidAppear | self.datasetSubBar.filterListView: %@", self.datasetSubBar.filterListView); 

NSLog(@"self.datasetSubBar.panels: %@", self.datasetSubBar.panels) 

。

2013-02-22 16:28:22.912 [5196:14003] viewDidAppear | self.datasetSubBar.filterListView: <UIScrollView: 0x8489f90; frame = (0 0; 768 934); clipsToBounds = YES; alpha = 0.8; gestureRecognizers = <NSArray: 0x848a650>; animations = { opacity=<CABasicAnimation: 0x98138b0>; }; layer = <CALayer: 0x848a160>; contentOffset: {0, 0}> 
2013-02-22 16:28:22.913 [5196:14003] self.datasetSubBar.panels: (
    "<DatasetFilterListPanelView: 0x9853570; frame = (-385 20; 365 165); tag = 1; layer = <CALayer: 0x9853640>>" 

感覺就像在子視圖的創建時，所述filterListView的寬度爲0的原因，如果上海華是768，子視圖錨應爲（383，20）{上海華的寬度（768） - 子視圖的寬度（ 365） - 填充（20）}。

這令我很沮喪，它應該工作。 UIScrollViews的行爲與約束不同嗎？

編輯：

是的，UIScrolView處理約束不同;我將滾動視圖更改爲一個UIView，並像它應該那樣工作。

Answer 1

做了更多挖掘和想通了，我需要在滾動視圖使用內容查看：

-(UIScrollView *)createFilterListView {  
    UIScrollView *scrollView = [UIScrollView new]; 
    scrollView.translatesAutoresizingMaskIntoConstraints = FALSE; 

    UIView *contentView = [UIView new]; 

    scrollView.contentView = contentView; 

    [scrollView addSubview:contentView]; 

    return scrollView; 
} 

又在哪裏滾動視圖實現，設置約束它，然後設置的內容查看和contentSize大小您需要：

[self.view layoutIfNeeded]; 

self.scrollView.contentView.frame = CGRectMake(0, 0, self.scrollView.frame.size.width, self.scrollView.frame.size.width * 2); 

self.scrollView.contentSize = CGSizeMake(self.scrollView.frame.size.width, self.scrollView.frame.size.width * 2); // made it twice as big to test scrolling 

我向UIScrollView添加了一個類別來存儲內容視圖。然後使用約束將項目添加到contentView。當您的項目需要滾動時，您需要調整contentView和contentSize的大小。

iOS 6 release notes也檢查了這一點。