objective-c - 以编程方式创建的 Tableview 为空

Question

Tableview 显示但为空，无法理解我忘记了什么：

#import <UIKit/UIKit.h>

@interface MenuViewController : UIViewController<UITableViewDataSource, UITableViewDelegate>
@property (strong, nonatomic) UITableView *table;
@end


#import "MenuViewController.h"

@interface MenuViewController ()

@end

@implementation MenuViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    _table.delegate = self;
    _table.dataSource = self;
    _table = [[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStylePlain];
    [self.view addSubview:_table];
    // Uncomment the following line to preserve selection between presentations.
    // self.clearsSelectionOnViewWillAppear = NO;

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem;
}
- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    NSLog(@"%s",__PRETTY_FUNCTION__);
    [_table reloadData];
}
- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return 4;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    if (cell == nil) {

        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];

    }

    cell.textLabel.text = @"text";

    // Configure the cell...

    return cell;
}
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return 25;
}

Answer 1

在实例化它之前，viewDidLoad您正在分配变量的dataSourceand 。因此，当您初始化变量时，它会覆盖已经存在的任何内容。delegate_table_table

如果您在分配委托和数据源之前移动初始化调用，它应该可以正常工作：

- (void)viewDidLoad
{
    [super viewDidLoad];
    _table = [[UITableView alloc]initWithFrame:self.view.bounds style:UITableViewStylePlain];
    _table.delegate = self;
    _table.dataSource = self;
    [self.view addSubview:_table];
}

Answer 2

只需评论这一行：

[self.view addSubview:_table];