dequeueReusableCellWithIdentifier

最新推荐文章于 2023-09-18 15:37:00 发布

dadalan

最新推荐文章于 2023-09-18 15:37:00 发布

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分类专栏： iphone 文章标签： object table performance access string iphone

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本文详细介绍了UITableView如何使用dequeueReusableCellWithIdentifier方法来提高性能。通过重用UITableViewCell对象，避免了不必要的对象创建，从而提升了应用程序效率。

dequeueReusableCellWithIdentifier:

Returns a reusable table-view cell object located by its identifier.

- (UITableViewCell *)dequeueReusableCellWithIdentifier:(NSString *)identifier

Parameters

identifier

A string identifying the cell object to be reused. By default, a reusable cell’s identifier is its class name, but you can change it to any arbitrary value.

Return Value

A UITableViewCell object with the associated identifier or nil if no such object exists in the reusable-cell queue.

Discussion

For performance reasons, a table view’s data source should generally reuseUITableViewCell objects when it assigns cells to rows in itstableView:cellForRowAtIndexPath: method. A table view maintains a queue or list ofUITableViewCell objects that the table view’s delegate has marked for reuse. It marks a cell for reuse by assigning it a reuse identifier when it creates it (that is, in theinitWithFrame:reuseIdentifier: method of UITableViewCell). The data source can access specific “template” cell objects in this queue by invoking thedequeueReusableCellWithIdentifier: method. You can access a cell’s reuse identifier through its reuseIdentifier property, which is defined by UITableViewCell.