Understanding the delegates in UITableView and UITableViewController

I am learning how to use the UITableView and UITableViewController in the iOS and I think I may have confused myself. I have created a simple TableView and I have 2 sections. Nothing complicated.

I have the following defined and it builds fine:

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

- (NSInteger)tableView:(UITableView *)tableView 
 numberOfRowsInSection:(NSInteger)section
{
    // Section is going to be either 0 or 1, high or low
    if (section == 0) {
        return 1;
    }
    else {
        return 2;
    }
}

However what I don't understand is the definitions of the methods. Both methods have to return an integer so I understand the starting (NSInteger). The numberOfRowsInSection starts with tableView:(UITableView *)tableView and I don't understand why?

I'm am new 开发者_如何学Cto programming the iOS so be gentle :-) All help greatly appreciated.

Mike

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The method name is "tableView:numberOfRowsInSection:". The first argument is the instance if UITableView which is asking the data source for the number of rows in a particular section. This is a useful convention as you might have a single object act as the data source for many table views or want to update the table view in some way when a delegate method is called. By passing the calling object to the delegate you avoid needing to have the delegate maintain an additional reference to that object.

Take a look at the NSURLConnection delegate methods dealing with authentication for an example of where this is really necessary.

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tableView:(UITableView *)tableView is helpful if you need to know which tableView sent that delegate method.

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This is Apple's naming convention for delegate and data source methods. numberOfSectionsInTableView: has no arguments other than the table view, so that argument is added at the end. tableView:numberOfRowsInSection: takes another argument, the index of the section in question. Apple has decided that, when there are other arguments, the calling object should go first, and the arguments come after that.

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Check out the UITableViewController Class Reference

- (NSInteger)tableView:(UITableView *)tableView 

The first part, NSInteger lets you know that you need to return a number return 1;, the second part (UITableView *)tableView lets you know that you are dealing with the UITableView class.