Swift 3 /如何在全局函数中调用tableView.reloadData（）？

Question

I'm trying to refactor a function to have it globally available. At the end of the function, a UITableView needs to be reloaded. I was thinking about passing the VC, but I still get

Value of type 'UIViewController' has no member 'tableView'

I know that I get that error because tableView is not part of a UIViewController by default, but how do I bypass it?

func downloadAvatar(_ userForAvatar: String, vc: UIViewController) {

    let whereClause = "objectId = '\(userForAvatar)'"
    let dataQuery = BackendlessDataQuery()
    dataQuery.whereClause = whereClause

    let dataStore = backendless?.persistenceService.of(BackendlessUser.ofClass())
    dataStore?.find(dataQuery, response: { (users : BackendlessCollection?) in

        let withUser = users?.data.first as! BackendlessUser
        let imgURL = withUser.getProperty("Avatar") as? String
        avatare.setValue(imgURL, forKey: userForAvatar)
        vc.tableView.reloadData() // problem here

    }) { (fault : Fault?) in
        print("error: \(fault)")
    }
}

Help is very appreciated.

Answer 1

'UIViewController' has no member 'tableView'

It tells everything ! Your vc is of type UIViewController , obviously it has no member named tableView .

You have used the parameter vc only once and its for reloading table. So instead of passing it, try passing the tableveiew reference itself.

Because of some reasons, if you cant do this and you should use ViewController itself, try create a protocol, implement it in all of your VCs and use that as type. tableview should be a member of that protocol

This is basic programming. Hope this helps

Answer 2

Instead of have having vc: UIViewController as an argument, you should just have tv: UITableView instead. Then instead of passing the view controller, you pass it's tableView. Although if this isn't working, you could try a completion block instead.

func downloadAvatar(_ userForAvatar: String, completion: @escaping () -> ()) {

    let whereClause = "objectId = '\(userForAvatar)'"
    let dataQuery = BackendlessDataQuery()
    dataQuery.whereClause = whereClause

    let dataStore = backendless?.persistenceService.of(BackendlessUser.ofClass())
    dataStore?.find(dataQuery, response: { (users : BackendlessCollection?) in

        let withUser = users?.data.first as! BackendlessUser
        let imgURL = withUser.getProperty("Avatar") as? String
        avatare.setValue(imgURL, forKey: userForAvatar)
        completion()

    }) { (fault : Fault?) in
        print("error: \(fault)")
    }
}

Then assuming you're calling this method from the respective view controller, you can reload the tableView data within the completion block.

downloadAvatar("$uid") { [weak self] in
     self?.tableView.reloadData()
}