tableview连接到数据源和委托-如何

Question

i am new to iOS, this may seem like a basic question. I have been working through this tutorial and I have no idea how the tableview is connected to the code. The sample project can be downloaded here .

I was my understanding that you need to extend UITableViewDelegate, UITableViewDataSource in the code, then in the storyboard you can drag from the tableview to them.

But what is perplexing is that the sample project does not extend UITableViewDelegate, UITableViewDataSource at all, therefore, how is the tableview in the story board connected to the code ?

Answer 1

Datasource is used to supply data and delegate is used to supply behaviour. UITableView asks your datasource every time it needs data to display. It provides a lot of flexibility for how you choose to represent your underlying data model. You simply define specific methods to use in order to get table information, and iOS can call them when it needs to know something like the number of rows in a section, or the content of a particular row.

You will probably implement your own delegate mechanism in the future. It is a great design pattern which handles interaction/data transfer between objects.

Answer 2

Because, the basic class adopts from UITableViewController

@interface WTTableViewController : UITableViewController

In your storyboard you just ctrl-drag from tableview to viewController and choose delegate and dataSource.

Answer 3

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewDataSource_Protocol/您应该参考此内容，这对您有很大帮助

Answer 4

If you working with TableViewController, UITableViewDelegate and UITableViewDataSource are connected to table automatically. In case you are working with ViewControler which contains TableView, you have to add UITableViewDelegate and UITableViewDataSource like this: @interface myViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> . In new versions of Xcode you can drag delegate and data source to table, and if you want to set delegate programmatically, you can add this two lines of codes:

[tableView setDelegate:self];
[tableView setDataSource:self];

or, equally:

tableview.delegate = self;
tableview.dataSource = self;

Answer 5

In viewcontroller.h file e declare the delegate and datasource method.

UIViewController<UITableViewDataSource,UITableViewDelegate>

then connect the delegate and datasource method with viewController so in viewController.m file

- (void)viewDidLoad {
tableview.delegate=self;
tableview.dataSource=self;
}

Answer 6

In Objective-C/iOS you often implement things by having classes conform to protocols rather than subclassing classes. WTTableViewController conforms to the protocols UITableViewDataSource: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewDataSource_Protocol/ and UITableViewDelegate: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UITableViewDelegate_Protocol/

In MainStoryboard.storyboard you can see in the inspector to the right that the TableViewController has a custom class of WTTableViewController

The relevant methods in WTTableViewController.m:

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 2;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 0;
}

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

    // Configure the cell...


    return cell;
}


#pragma mark - Table view delegate

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Navigation logic may go here. Create and push another view controller.
}

Here's some general info about protocols: https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/WorkingwithProtocols/WorkingwithProtocols.html

I suggest reading a beginners book or tutorial on iOS to pick up the overall design principles otherwise many things can be quite confusing.