ios - 我正在尝试在选择行时向 tableview 单元格中的 UIStackView 添加对象和删除对象 - 它只工作一次

Question

所以我尝试使用委托(delegate) -didSelectRowAtIndexPath 将 UIDatePicker 添加到 UITableView 单元格内的 UIStackView。当我选择行并取消选择该行时，它只起作用一次，不会再次重复该操作。

Stack View 位于 tableview 单元格内并包含一个标签。日期选择器位于场景停靠栏中。

在 -didSelectRowAtIndexPath 方法中，我正在检查堆栈 View 是否包含日期选择器，如果不包含则添加它，否则将其删除。它只工作一次。

代码如下:

 #import "MyTableViewController.h"

@interface MyTableViewController ()
@property (strong, nonatomic) IBOutlet UIDatePicker *extraPicker;
@property (nonatomic, strong) UIStackView *stackView; //tag 100

@end

@implementation MyTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.tableView.estimatedRowHeight = 44;
    self.tableView.rowHeight = UITableViewAutomaticDimension;

}

#pragma addPickerViewToStackView

-(void)addPickerViewToStackView{

    [_stackView addArrangedSubview:_extraPicker];
}

#pragma mark - remove picker
-(void)removePickerFromStackView{

    [UIView animateWithDuration:0.4
                     animations:^{ [_extraPicker setAlpha:0];
                         [_extraPicker.widthAnchor constraintEqualToConstant:self.view.frame.size.width].active = true;
                         [_stackView removeArrangedSubview:_extraPicker];
                         [self.tableView layoutIfNeeded];
                     }];
}




#pragma mark - picker date changed
-(IBAction)pickerValeChanged:(id)sender{
    [self.tableView reloadData];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {

    return 2;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if (section == 0) {
        return 3;
    }else if (section == 1){
        return 1;
    }
    return 0;

}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"otherCell" forIndexPath:indexPath];
    cell.textLabel.text = @"Starts";

    if (indexPath.row == 2) {
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"pickerCell" forIndexPath:indexPath];
        _stackView = (UIStackView*) [cell viewWithTag:100];
        return cell;
    }

    return cell;
}


-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{

    [self.tableView beginUpdates];
    [_extraPicker setAlpha:1];

    if (indexPath.row == 1) {
        if ([_extraPicker isDescendantOfView:_stackView]) {
            [self removePickerFromStackView];
        }else if (![_extraPicker isDescendantOfView:_stackView]){
        [self addPickerViewToStackView];
        }

    }


    [self.tableView endUpdates];
    [tableView deselectRowAtIndexPath:indexPath animated:YES];

}


@end

Answer 1

在阅读了 Apple 网站上的 UIStackView 文档后，我了解到以下重要信息:

This method removes the provided view from the stack’s arrangedSubviews array. The view’s position and size will no longer be managed by the stack view. However, this method does not remove the provided view from the stack’s subviews array; therefore, the view is still displayed as part of the view hierarchy.

To prevent the view from appearing on screen after calling the stack’s removeArrangedSubview: method, explicitly remove the view from the subviews array by calling the view’s removeFromSuperview method, or set the view’s hidden property to YES.

所以我的错误是没有从 superView 中删除 _extraPicker。在 -removePickerFromStackView 中添加此代码后，一切正常。

[_extraPicker removeFromSuperview];