UITableView -registerClass:forCellReuseIdentifier:

 

In iOS 6, 2 new methods -registerClass:forCellReuseIdentifier: and -dequeueReusableCellWithIdentifier:forIndexPath: were added to UITableView.

 

Prior to this, you would write code like the following when you need a UITableView cell instance:

 

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

NSString* cellIdentifier = @"MyTableViewCellIdentifier";

UITableViewCell* cell = aTableView.dequeueReusableCellWithIdentifier(cellIdentifier)

if (!cell) {

  cell = [[UITableView alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];

}

 

//config cell

return cell;

}

 

Starting with iOS 6, you can do this instead:

 

- (void)viewDidLoad {

[super viewDidLoad];

NSString* cellIdentifier = @"MyTableViewCellIdentifier";

[self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:cellIdentifier];

}

 

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

NSString* cellIdentifier = @"MyTableViewCellIdentifier";

UITableViewCell* cell = aTableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath:indexPath)

//config cell. cell is always non-nil and the cell will have the correct height as returned by -tableView:heightForRowAtIndexPath:.

return cell;

}

 

-dequeueReusableCellWithIdentifier:forIndexPath: always return a valid cell so we can skip the nil check. The cell will also have the correct height as returned by -tableView.heightForRowAtIndexPath:

 

Note that using this, all cells created will have the style UITableViewCellStyleDefault unless we use a UITableViewCell subclass.

转载地址：http://tinyletter.com/iosdev/letters/ios-dev-tip-50-uitableview-registerclass-forcellreuseidentifier