Swift: ScrollView 中的两个tableView

Question

我使用 Xcode 8.0 和 swift 2.3。

我有一个scrollView，我想用segment来控制页面

http://imgur.com/a/KZFIS

scrollView中有两个tableView

但是函数中出现错误:

   func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

Contstant 'cell' used before being initialized

这是错误

http://imgur.com/a/nooVG

这是初始化“cell”，对吧？

 let cell:UITableViewCell?

上面是我的代码

class DetailViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UIScrollViewDelegate  {
@IBOutlet weak var scroll: UIScrollView!
@IBOutlet weak var segmentControl2: UISegmentedControl!

@IBOutlet var recipesImageView: UIImageView!
@IBOutlet var tableView:UITableView!
@IBOutlet var tableView1:UITableView!
var recipes:Recipe!
var noodles:Recipe!
var snacks:Recipe!
var category: Int = Int()

@IBAction func segmented(sender: AnyObject) {
    switch sender.selectedSegmentIndex {
        case 0:
            scroll.setContentOffset(CGPoint(x:0, y:0), animated: true)
        case 1:
            scroll.setContentOffset(CGPoint(x:375, y:0), animated: true)
        case 2:
            scroll.setContentOffset(CGPoint(x:750, y:0), animated: true)
        case 3:
            scroll.setContentOffset(CGPoint(x:1125, y:0), animated: true)


        default:
            print()
    }
}

override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
    switch self.category {
        case 0:
            self.recipesImageView.image = UIImage(named: recipes.image)
            title = self.recipes.name
        case 1:
            self.recipesImageView.image = UIImage(named: noodles.image)
            title = self.noodles.name
        case 2:
            self.recipesImageView.image = UIImage(named: snacks.image)
            title = self.snacks.name
        case 3:
            self.recipesImageView.image = UIImage(named: noodles.image)
            title = self.noodles.name
        case 4:
            self.recipesImageView.image = UIImage(named: noodles.image)
            title = self.noodles.name
        default:
            self.recipesImageView.image = UIImage(named: recipes.image)
            title = self.recipes.name
    }

    self.tableView.backgroundColor = UIColor(red: 240.0/255.0, green: 240.0/255.0, blue: 240.0/255.0, alpha: 0.5)

    //刪除多餘的隔線
    self.tableView.tableFooterView = UIView(frame: CGRectZero)

    self.tableView.separatorColor = UIColor(red: 240.0/255.0, green: 240.0/255.0, blue: 240.0/255.0, alpha: 1)

    //title = self.recipes.name

    tableView.estimatedRowHeight = 36.0;
    tableView.rowHeight = UITableViewAutomaticDimension;

    tableView.dataSource = self
    tableView.delegate = self
    tableView.registerClass(UITableViewCell.self, forCellReuseIdentifier: "Cell")

    tableView1.dataSource = self
    tableView1.delegate = self
    tableView1.registerClass(UITableViewCell.self, forCellReuseIdentifier: "Cell1")

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    var cellNum:Int?
    if tableView == self.tableView {
        cellNum = 4
        //return cellNum
    }

    if tableView == self.tableView1 {
        cellNum = 1
    }
    return cellNum!
}



func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let cell:UITableViewCell?

    if tableView == self.tableView {
         let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! DetailTableViewCell
        //cell.backgroundColor = UIColor.clearColor()
        if self.category == 0 {
            switch indexPath.row {
            case 0:
                cell.fieldLabel.text = "名稱"
                cell.valueLabel.text = recipes.name
                cell.amountLabel.text = ""

            case 1:
                cell.fieldLabel.text = "類型"
                cell.valueLabel.text = recipes.type
                cell.amountLabel.text = ""

            case 2:
                cell.fieldLabel.text = "收藏"
                cell.valueLabel.text = (recipes.isFavor) ? "Yes" : "No"
                cell.amountLabel.text = ""

            case 3:
                cell.fieldLabel.text = "食材"
                cell.valueLabel.text = recipes.material
                cell.amountLabel.text = recipes.amount
            default:
                cell.fieldLabel.text = ""
                cell.valueLabel.text = ""
                cell.amountLabel.text = ""
            }
        }

        if self.category == 1 {
            switch indexPath.row {
            case 0:
                cell.fieldLabel.text = "名稱"
                cell.valueLabel.text = noodles.name
                cell.amountLabel.text = ""

            case 1:
                cell.fieldLabel.text = "類型"
                cell.valueLabel.text = noodles.type
                cell.amountLabel.text = ""

            case 2:
                cell.fieldLabel.text = "收藏"
                cell.valueLabel.text = (noodles.isFavor) ? "Yes" : "No"
                cell.amountLabel.text = ""

            case 3:
                cell.fieldLabel.text = "食材"
                cell.valueLabel.text = noodles.material
                cell.amountLabel.text = noodles.amount
            default:
                cell.fieldLabel.text = ""
                cell.valueLabel.text = ""
                cell.amountLabel.text = ""
            }
        }

        if self.category == 2 {
            switch indexPath.row {
            case 0:
                cell.fieldLabel.text = "名稱"
                cell.valueLabel.text = snacks.name
                cell.amountLabel.text = ""

            case 1:
                cell.fieldLabel.text = "類型"
                cell.valueLabel.text = snacks.type
                cell.amountLabel.text = ""

            case 2:
                cell.fieldLabel.text = "收藏"
                cell.valueLabel.text = (snacks.isFavor) ? "Yes" : "No"
                cell.amountLabel.text = ""

            case 3:
                cell.fieldLabel.text = "食材"
                cell.valueLabel.text = snacks.material
                cell.amountLabel.text = snacks.amount
            default:
                cell.fieldLabel.text = ""
                cell.valueLabel.text = ""
                cell.amountLabel.text = ""
            }
        }

        if self.category == 3 {
            switch indexPath.row {
            case 0:
                cell.fieldLabel.text = "名稱"
                cell.valueLabel.text = noodles.name
                cell.amountLabel.text = ""

            case 1:
                cell.fieldLabel.text = "類型"
                cell.valueLabel.text = noodles.type
                cell.amountLabel.text = ""

            case 2:
                cell.fieldLabel.text = "收藏"
                cell.valueLabel.text = (noodles.isFavor) ? "Yes" : "No"
                cell.amountLabel.text = ""

            case 3:
                cell.fieldLabel.text = "食材"
                cell.valueLabel.text = noodles.material
                cell.amountLabel.text = noodles.amount
            default:
                cell.fieldLabel.text = ""
                cell.valueLabel.text = ""
                cell.amountLabel.text = ""
            }
        }

        if self.category == 4 {
            switch indexPath.row {
            case 0:
                cell.fieldLabel.text = "名稱"
                cell.valueLabel.text = noodles.name
                cell.amountLabel.text = ""

            case 1:
                cell.fieldLabel.text = "類型"
                cell.valueLabel.text = noodles.type
                cell.amountLabel.text = ""

            case 2:
                cell.fieldLabel.text = "收藏"
                cell.valueLabel.text = (noodles.isFavor) ? "Yes" : "No"
                cell.amountLabel.text = ""

            case 3:
                cell.fieldLabel.text = "食材"
                cell.valueLabel.text = noodles.material
                cell.amountLabel.text = noodles.amount
            default:
                cell.fieldLabel.text = ""
                cell.valueLabel.text = ""
                cell.amountLabel.text = ""
            }
        }
            //return cell
    }

    if tableView == self.tableView1 {
           let cell = tableView1.dequeueReusableCellWithIdentifier("Cell1",    forIndexPath: indexPath) as! DetailTableViewCell

        if self.category == 0 {
            switch indexPath.row {
            case 0:
                cell.materialLabel!.text = recipes.material
            default:
                cell.materialLabel!.text = recipes.material
            }
        }
        if self.category == 1 {
            switch indexPath.row {
            case 0:
                cell.materialLabel!.text = noodles.material
            default:
                cell.materialLabel!.text = noodles.material
            }
        }
        if self.category == 2 {
            switch indexPath.row {
            case 0:
                cell.materialLabel!.text = snacks.material
            default:
                cell.materialLabel!.text = snacks.material
            }
        }
        if self.category == 3 {
            switch indexPath.row {
            case 0:
                cell.materialLabel!.text = noodles.material
            default:
                cell.materialLabel!.text = noodles.material
            }
        }
        if self.category == 4 {
            switch indexPath.row {
            case 0:
                cell.materialLabel!.text = noodles.material
            default:
                cell.materialLabel!.text = noodles.material
            }
        }
    }

    return cell   //<----This line will error ***********************
}


//避免被前面一頁的隱藏導覽列所影響
override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(animated)

    self.navigationController?.hidesBarsOnSwipe = false
    self.navigationController?.setNavigationBarHidden(false, animated: true)
}

/*
 // MARK: - Navigation

 // In a storyboard-based application, you will often want to do a little preparation before navigation
 override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
 // Get the new view controller using segue.destinationViewController.
 // Pass the selected object to the new view controller.
 }
 */

}

Answer 1

我相信这些改变应该有所帮助:

1. 将 let cell:UITableViewCell? 更改为 let cell:UITableViewCell。该函数不希望您返回可选值。

2. 将 let cell = tableView.dequeue... 更改为 cell = tableView.dequeue...。您不应声明 cell 两次。

3. 将 cellForRowAtIndexPath 中的结构更新为:

if tableView == self.tableView {
细胞=...
...
} 别的 {
细胞=...
...
}
返回单元格

因此编译器会发现您总是在返回单元格之前将其设置为某些内容。