在iOS Carplay中延迟加载数据

  • Z时代
  • 2024-01-10
  • 分类：问答

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？

回答：

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
}

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