以编程方式为 UITableView 和 UISearchBar 设置 NSLayoutConstraints

Question

我有一个UIViewController，它确实在它的-viewDidLoad 方法中添加了一个UISearchBar 和一个UITableView，作为它的view 属性的子视图。添加这些之后，我使用如下可视格式语言创建约束：

NSDictionary *views = @{@"searchBar": [_searchController searchBar],
                        @"dataTable": [self tableView]};

NSArray *horizontalSearchBarConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[searchBar]|"
                                                                                  options:0
                                                                                  metrics:nil
                                                                                    views:views];
NSArray *horizontalDataTableConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[dataTable]|"
                                                                                  options:0
                                                                                  metrics:nil
                                                                                    views:views];
NSArray *verticalSearchBarDataTableConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[searchBar(44)][dataTable]|"
                                                                                         options:0
                                                                                         metrics:nil
                                                                                           views:views];
NSMutableArray *allConstraints = [NSMutableArray new];
[allConstraints addObjectsFromArray:horizontalDataTableConstraints];
[allConstraints addObjectsFromArray:horizontalSearchBarConstraints];
[allConstraints addObjectsFromArray:verticalSearchBarDataTableConstraints];

[[self view] addConstraints:allConstraints];

阅读：宽度应该是整个屏幕的宽度，searchBar 的高度应该正好是 44，dataTable 的高度应该从searchBar 的底部延伸到视图的底部.

在此之前，我将这些视图的 translatesAutoresizingMaskIntoConstraints 设置为 NO。 UIViewController 本身以模态视图呈现。我们说的是 iOS 6。

我得到的是：一个空的视图。就是纯白。

我错过了什么？我还是 Auto Layout 的新手，并尝试围绕它进行思考。

谢谢！

更新：添加整个-viewDidLoad

- (void)viewDidLoad {
    [super viewDidLoad];    
    BOOL translatesAutoreszingMaskIntoConstraints = NO;

    [[self view] setTranslatesAutoresizingMaskIntoConstraints:translatesAutoreszingMaskIntoConstraints];

    // manually create the search bar
    UISearchBar *searchBar = [[UISearchBar alloc] init];
    [searchBar setDelegate:self];
    [searchBar setShowsCancelButton:NO];
    [searchBar setTranslatesAutoresizingMaskIntoConstraints:translatesAutoreszingMaskIntoConstraints];

    // create the search bar controller
    _searchController = [[UISearchDisplayController alloc] initWithSearchBar:searchBar contentsController:self];
    [_searchController setDelegate:self];
    [[_searchController searchResultsTableView] setDelegate:self];
    [_searchController setSearchResultsDataSource:self];
    [_searchController setSearchResultsDelegate:self];

    // add the search bar
    [[self view] addSubview:[_searchController searchBar]];

    // manually create the table view and add it to the view
    _tableView = [[UITableView alloc] initWithFrame:CGRectZero style:UITableViewStyleGrouped];
    [_tableView setBackgroundView:nil];
    [_tableView setSeparatorStyle:UITableViewCellSeparatorStyleSingleLineEtched];
    [_tableView setSeparatorColor:NEA_COLOR_MEDIUM_GREY];
    [_tableView setBackgroundColor:NEA_COLOR_VIEW_BACKGROUND];
    [_tableView setDataSource:self];
    [_tableView setDelegate:self];
    [_tableView setTranslatesAutoresizingMaskIntoConstraints:translatesAutoreszingMaskIntoConstraints];

    [[self view] addSubview:[self tableView]];

    // set up the layout using Auto Layout
    NSDictionary *views = @{@"searchBar": [_searchController searchBar],
                            @"dataTable": [self tableView]};

    NSArray *horizontalSearchBarConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[searchBar]|"
                                                                                      options:0
                                                                                      metrics:nil
                                                                                        views:views];
    NSArray *horizontalDataTableConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[dataTable]|"
                                                                                      options:0
                                                                                      metrics:nil
                                                                                        views:views];
    NSArray *verticalSearchBarDataTableConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[searchBar(44)][dataTable]|"
                                                                                             options:0
                                                                                             metrics:nil
                                                                                               views:views];

    NSMutableArray *allConstraints = [NSMutableArray new];
    [allConstraints addObjectsFromArray:horizontalDataTableConstraints];
    [allConstraints addObjectsFromArray:horizontalSearchBarConstraints];
    [allConstraints addObjectsFromArray:verticalSearchBarDataTableConstraints];

    [[self view] addConstraints:allConstraints];

    // add our little gradient
    UIImage *shadow = [UIImage imageNamed:@"searchbar_bg_shadow"];
    UIImageView *shadowView = [[UIImageView alloc] initWithImage:shadow];
    [shadowView setFrame:CGRectMake(0, 44, 900, 14)];
    [shadowView setBackgroundColor:[UIColor clearColor]];
    [shadowView setTranslatesAutoresizingMaskIntoConstraints:YES];
    [[self view] addSubview:shadowView];

    // add the cancel button for the search bar
    UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"ui_navigationbar_close"] style:UIBarButtonItemStyleBordered target:self action:@selector(cancel:)];
    [[self navigationItem] setRightBarButtonItem:cancelButton];

    // set a short back button title
    UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@" " style:UIBarButtonItemStyleBordered target:nil action:nil];
    self.navigationItem.backBarButtonItem = backButton;
}

更新：附加信息

封装UINavigationController 是通过情节提要创建的。在那里，将UIViewController 添加到我的班级，因为它是rootViewController。就是这样。

当我在该格式字符串中手动添加宽度时，它会显示视图。因此，当我手动指定尺寸时，它可以工作。但是，我想，我可以简单地使用框架来代替......

Answer 1

我不知道您的问题是否已解决，但我注意到您的代码中存在潜在问题。

试着去掉下面这行代码：

[[self view] setTranslatesAutoresizingMaskIntoConstraints:translatesAutoreszingMaskIntoConstraints];

对于根视图，不要将该属性设置为 NO。