快速使用带有NSUserDefaults的字典

Question

I'm trying to learn about dictionaries and nsusersdefaults in swift. I wrote a small program that creates a dictionary of strings and uses that dictionary to populate a tableview. Next I save the dictionary to NSUserDefaults. Everything at this point is working great. It's when I attempt to pull the dictionary back out and use it that things go wrong.

Here is my complete code, the error is on the line myDict = userDefaults and the error is Cannot assign a value of type '[String : AnyObject]' to a value of type '[Dictionary]':

import UIKit


// Create dictionary
var myDict = [Dictionary<String,String>()]


class TableViewController: UITableViewController {

override func viewDidLoad() {
    super.viewDidLoad()

    print(myDict.count)

    // Dictionary starts out with 1 item when new
    // so remove that one thing and create it if needed

    if myDict.count == 1 {

        myDict.removeAtIndex(0)

        // Put some stuff in the dictionary

        myDict.append(["name":"Bill","age":"39","sex":"male"])
        myDict.append(["name":"Nick","age":"8","sex":"male"])
        print(myDict)


    } else {

        if let userDefaults = NSUserDefaults.standardUserDefaults().dictionaryForKey("myDict") {

            myDict = userDefaults


        }

    }

}


override func viewDidAppear(animated: Bool) {
    NSUserDefaults.standardUserDefaults().setObject(myDict, forKey: "myDict")
}

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



// MARK: - Table view data source

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    // #warning Incomplete implementation, return the number of sections
    return 1
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of rows
    return myDict.count
}


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

    // Configure the cell...

    cell.textLabel!.text = myDict[indexPath.row]["name"]

    return cell
 }
}

Answer 1

var myDict = [Dictionary<String,String>()]

should be

var myDict = [String:String]()

at least in swift 2.0

For your problem it should actually be

var myDict = [String:AnyObject]()

because that is what you get from NSUserdefaults. When you access a value from a key in the dictionary you need to cast it to String.

Answer 2

Instead of setObject use the sync method :

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];        
    if (![defaults objectForKey:@"vesselType_preference"])
    {
        [defaults setObject:@"Dry" forKey:@"vesselType_preference"];
    }
    [[NSUserDefaults standardUserDefaults] synchronize];