用户在Carplay中滚动时如何延迟加载项目?
我正在使用MPPlayableContentDataSource中的beginLoadingChildItems加载 第一组项目,但是当用户滚动到 页面底部时如何调用下一页?
The way you can achieve this is inside the following function:
func beginLoadingChildItems(at indexPath: IndexPath, completionHandler: @escaping (Error?) -> Void)
As Example:
if (indexPath[componentIndex] + 1) % Threshold == 0 { // Threshold is Your Defined Batch Size // Load the next corresponding batch }
Load your lazy data, then call:
completionHandler(nil) // In case of no error has occurred
,but firstly, you need to return the total items count correctly in the following function:
func numberOfChildItems(at indexPath: IndexPath) -> Int
Something like the below,
class YourDataSource : MPPlayableContentDataSource { private var items = [MPContentItem]() private var currentBatch = 0 func beginLoadingChildItems(at indexPath: IndexPath, completionHandler: @escaping (Error?) -> Void) { // indexPath[1]: is current list level, as per CarPlay list indexing (It's an array of the indices as ex: indexPath = [0,1] means Index 0 in the first level and index 1 at the second level). // % 8: Means each 8 items, I will perform the corresponding action. // currentBatch + 1 == nextBatch, This check in order to ensure that you load the batches in their sequences. let currentCount = indexPath[1] + 1 let nextBatch = (currentCount / 8) + 1 if currentCount % 8 == 0 && currentBatch + 1 == nextBatch { // Load the next corresponding batch YourAPIHandler.asyncCall { newItems in self.currentBatch = self.currentBatch + 1 items.append(newItems) completionHandler(nil) MPPlayableContentManager.shared().reloadData() } } else { completionHandler(nil) } } } func numberOfChildItems(at indexPath: IndexPath) -> Int { return self.items.count }