对自定义UITableView单元进行故障排除[快速]

Question

I have created a custom UITableView cell in my Storyboard that looks like this:

I hooked it up to my UITableViewCell class like this:

import UIKit

class StatusCell: UITableViewCell {

@IBOutlet weak var InstrumentImage: UIImageView!

@IBOutlet weak var InstrumentType: UILabel!

@IBOutlet weak var InstrumentValue: UILabel!

override func awakeFromNib() {
    super.awakeFromNib()
}

override func setSelected(selected: Bool, animated: Bool) {
    super.setSelected(selected, animated: animated)
}
}

Finally I attempted to initialize the UITableView from my UIViewController as such:

import UIKit

class SecondViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {

@IBOutlet weak var TableView: UITableView!

let Items = ["Altitude","Distance","Groundspeed"]

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.Items.count
}

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

    var cell: StatusCell! = tableView.dequeueReusableCellWithIdentifier("Cell") as StatusCell!

    cell.InstrumentType?.text = Items[indexPath.row]
    cell.InstrumentValue?.text = "150 Km"
    cell.InstrumentImage?.image = UIImage(named: Items[indexPath.row])
    return cell
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

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

}

However, when I attempt to run the program I get an EXC_BAD_INSTRUCTION error:

What could I have done wrong? Any help would be appreciated!

Answer 1

The debugger output shows that cell is nil , meaning it could not be instantiated. Furthermore, you are forcing an unwrapping of the optional (using the ! ) which causes the app to crash on the nil value.

Try to change your cellForRowAtIndexPath method like so (notice the dequeueReusableCellWithIdentifier method):

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as StatusCell

    cell.InstrumentType.text = Items[indexPath.row]
    cell.InstrumentValue.text = "150 Km"
    cell.InstrumentImage.image = UIImage(named: Items[indexPath.row])

    return cell
}

Assuming that your custom tableViewCell class is correctly set up and the outlets are bound, there is no need to check for optionals.

Place a breakpoint on the let cell = ... line and step through the code. Check if cell gets initialized and is not nil .

And please: Do not use upper case names for properties and variables (your outlets, Items array...) as upper case names are for classes, structs, ...