Question

我有一个带表的视图控制器。第一次创建并显示单元格时，将按顺序调用以下功能（除了视图控制器功能外）：

....
func viewWillAppear(_ animated: Bool)

func cellForRow(at indexPath: IndexPath) -> UITableViewCell? 

optional func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath)

func viewWillDisappear(_ animated: Bool)
....

当我退出屏幕an时，将调用以下功能。

....
func viewWillAppear(_ animated: Bool)

func viewWillDisappear(_ animated: Bool)
....

但是为什么在willDisplaycell和viewWillAppear之间没有调用viewWillDisappear？

日志为：

viewWillAppear
cellForRowAtIndexPath: 0 
willDisplayCell: 0 
cellForRowAtIndexPath: 1 
willDisplayCell: 1 
cellForRowAtIndexPath: 2 
willDisplayCell: 2 
viewWillDisappear
viewWillAppear
viewWillDisappear

代替：

viewWillAppear
cellForRowAtIndexPath: 0 
willDisplayCell: 0 
cellForRowAtIndexPath: 1 
willDisplayCell: 1 
cellForRowAtIndexPath: 2 
willDisplayCell: 2 
viewWillDisappear
viewWillAppear
willDisplayCell: 0 
willDisplayCell: 1 
willDisplayCell: 2 
viewWillDisappear

Answer 1

我最终要做的是检查viewDidAppear中显示了哪些单元格。不确定这是最好的答案，所以不要犹豫，添加更好的答案。

INSERT INTO contacts (id, data)
VALUES ({uuid} :: {dataObject} jsonb)
ON CONFLICT (
(data->>'customerId'),
LOWER(COALESCE(data->'data'->'profile'->'location'->>'formatted', '')),
LOWER(COALESCE(data->'data'->'profile'->'name'->'anglican'->>'given', '')),
LOWER(COALESCE(data->'data'->'profile'->'name'->'anglican'->>'middlename', '')),
LOWER(COALESCE(data->'data'->'profile'->'name'->'anglican'->>'surname', '')),
LOWER(COALESCE(data->'data'->'profile'->'name'->'anglican'->>'suffix', '')),
LOWER(COALESCE(data->'data'->'profile'->'name'->'anglican'->>'title', ''))
      )
      WHERE deleted = false and duplicated = false
      DO UPDATE
      SET data =
      jsonb_build_object(
        'id', contacts.id,
        'data', jsonb_build_object(
          'fields',(contacts.data->'data'->>'fields')::jsonb || (excluded.data->'data'->>'fields')::jsonb,
          'profile',(excluded.data->'data'->>'profile')::jsonb,
          'status',contacts.data->'data'->>'status',
          'contacted',contacts.data->'data'->>'contacted',
          'successful',contacts.data->'data'->>'successful',
          'reservation',(contacts.data->'data'->>'reservation')::jsonb
        ),
        'meta', jsonb_build_object(
          'etag',contacts.data->'meta'->>'etag',
          'created',contacts.data->'meta'->>'created',
          'modified',excluded.data->'meta'->>'modified',
          'resource',contacts.data->'meta'->>'resource',
          'createdBy',contacts.data->'meta'->>'createdBy',
          'isDeleted',contacts.data-> 'meta'->>'isDeleted',
          'modifiedBy',excluded.data->'meta'->>'modifiedBy'
        ),
        'customerId',contacts.data->>'customerId',
        'securityGroupId',contacts.data->>'securityGroupId'
      )
      RETURNING *;

为什么第二次不调用willDisplayCell

1 个答案: