不要在水平紧凑的环境中折叠 UISplitViewController

Question

UISplitViewController 的默认行为是当它从水平规则过渡到水平紧凑环境时折叠。是否有可能以某种方式覆盖它？

由于某些设计解决方案，我希望 splitView 始终扩展。我没有在 UISplitViewController 的文档中找到解决方案：属性 collapsed 是只读的，委托方法仅适用于 "how to collapse"，但不适用于 "don't collapse at all"。我正在使用 iOS9 SDK。

Answer 1

我明白了。文档状态：

The split view controller determines the arrangement of its child view controllers based on the available space. In a horizontally regular environment, the split view controller presents its view controllers side-by-side whenever possible. In a horizontally compact environment, the split view controller acts more like a navigation controller, displaying the primary view controller initially and pushing or popping the secondary view controller as needed.

所以 splitView 在 Compact 水平环境下总是折叠，在 Regular 下展开。解决方法就是在我们要展开的时候告诉splitView它有Regular horizontal environment。这个想法取自 WWDC 2014 Video "Building Adaptive Apps with UIKit". Unfortunately, the sample code 他们在视频中提到的不包括这种情况。但是我们的想法是为 SplitViewController 创建包含 ViewController，我们可以使用方法 setOverrideTraitCollection:forChildViewController:

覆盖 SplitViewController 的特征集合

@implementation ContainingViewController

- (instancetype)initWithNibName:(nullable NSString *)nibNameOrNil bundle:(nullable NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nil bundle:nil];
    if (self)
    {
        _splitViewController = [[UISplitViewController alloc] initWithNibName:nil bundle:nil];
        _splitViewController.viewControllers = <view controllers>;

        [self addChildViewController:_splitViewController];
        [self.view addSubview:_splitViewController.view];

        UITraitCollection *horizontallyRegularTraitCollection = [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassRegular];
        [self setOverrideTraitCollection:horizontallyRegularTraitCollection forChildViewController:_splitViewController];
    }
    return self;
}

通过这段代码，SplitViewController 将始终具有 Regular 水平特征集合，从而扩展。

不要在水平紧凑的环境中折叠 UISplitViewController

Don't collapse UISplitViewController in horizontally compact environment

iphone

cocoa-touch

ipad

uisplitviewcontroller

ios