设置UITableView Delegate和DataSource [英] Set UITableView Delegate and DataSource

问题描述

这是我的问题：
我的故事板中有这个小的 UITableView ：

这是我的代码：

SmallTableViewController.h

#import <UIKit/UIKit.h>
#import "SmallTable.h"

@interface SmallViewController : UIViewController

@property (weak, nonatomic) IBOutlet UITableView *myTable;

@end

SmallTableViewController.m / p>

SmallTableViewController.m

#import "SmallViewController.h"

@interface SmallViewController ()

@end

@implementation SmallViewController
@synthesize myTable = _myTable;

- (void)viewDidLoad
{
    SmallTable *myTableDelegate = [[SmallTable alloc] init];
    [super viewDidLoad];
    [self.myTable setDelegate:myTableDelegate];
    [self.myTable setDataSource:myTableDelegate];

    // Do any additional setup after loading the view, typically from a nib.
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

@end

现在你可以看到，我想设置一个名为myTableDelegate的实例作为myTable的Delegate和DataSource。

Now as you can see, I want to set an instance called myTableDelegate as Delegate and DataSource of myTable.

这是SmallTable类的源。

This is the Source of SmallTable class.

SmallTable.h

#import <Foundation/Foundation.h>

@interface SmallTable : NSObject <UITableViewDelegate , UITableViewDataSource>

@end

SmallTable.m / p>

SmallTable.m

@implementation SmallTable

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 0;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return 5;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    // Configure the cell...
    cell.textLabel.text = @"Hello there!";

    return cell;
}

#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSLog(@"Row pressed!!");
}

@end

我实现了所有的<$应用程序需要的c $ c> UITableViewDelegate 和 UITableViewDataSource 方法。为什么在视图出现之前崩溃？

I implemented all the UITableViewDelegate and UITableViewDataSource method that the app need. Why it just crash before the view appear??

谢谢!!

推荐答案

rickster是对的但是，由于您的 viewDidLoad 方法结束后，您可能需要为您的资源使用 strong 限定符无论如何，将被释放。

rickster is right. But I guess you need to use a strong qualifier for your property since at the end of your viewDidLoad method the object will be deallocated anyway.

@property (strong,nonatomic) SmallTable *delegate;

// inside viewDidload

[super viewDidLoad];
self.delegate = [[SmallTable alloc] init];    
[self.myTable setDelegate:myTableDelegate];
[self.myTable setDataSource:myTableDelegate];

但是有没有任何理由为您的表使用单独的对象（数据源和委托）？为什么不将 SmallViewController 作为表的来源和委托？

But is there any reason to use a separated object (data source and delegate) for your table? Why don't you set SmallViewController as both the source and the delegate for your table?

另外你是不以正确的方式创建单元格。这些行不做任何事情：

In addition you are not creating the cell in the correct way. These lines do nothing:

static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

// Configure the cell...
cell.textLabel.text = @"Hello there!";

dequeueReusableCellWithIdentifier 只需从表cache 一个已经创建并可以重用的单元格（这可以避免内存消耗），但是你没有创建任何内容。

dequeueReusableCellWithIdentifier simply retrieves from the table "cache" a cell that has already created and that can be reused (this to avoid memory consumption) but you haven't created any.

你在哪里 alloc-init ？这样做：

static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(!cell) {
    cell = // alloc-init here
}
// Configure the cell...
cell.textLabel.text = @"Hello there!";

此外，请向 numberOfSectionsInTableView 返回1的0：

Furthermore say to numberOfSectionsInTableView to return 1 instead of 0:

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

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