Swift-数据类型问题

Question

I am loading some data into NSUserDefaults on application startup and when the user views the according View loading the data out into a TableView. I'm having an issue with the data types though and always seem to get an error whichever way I try.

Where am I going wrong. I am skipping some code and only giving the important parts. I keep getting errors like "Can't assign Bool to AnyObject"

// startup function which loads the data
var categorys : [[String:Bool]] = [["All": true]]
for (index: String, category: JSON) in output {
    categorys.append([category["name"].string!: true])
}
NSUserDefaults.standardUserDefaults().setObject(categorys, forKey: "categorys")


// view controller

class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    var categorys: [[String:Bool]] = []

    func buildTableView() {
        if let categorys = NSUserDefaults.standardUserDefaults().arrayForKey("categorys") {
            for category in categorys {
                self.categorys.append([category["name"] as! String: category["selected"] as! Bool])
            }
            // Was trying to just assign straight away but fails
            // self.categorys = categorys
        }
    }


// then later on I want to be able to do the following
    func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        cell.textLabel?.text = self.categorys[indexPath.row]["name"] as? String
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        if (self.categorys[indexPath.row]["selected"] as? Bool == true) {
            self.categorys[indexPath.row]["selected"] = "false"
        }
    }
}

I should probably also mention i was trying a different datatype before which is more logical for my usage but also had similar issues.

["name": [category["name"].string!, "selected": true]]

I should also mention this is data for my tableview and I want to update the boolean value for if the cell is selected to not.

Answer 1

In order to use Bool in NSUserDefaults , you must use setBool: forKey: :

NSUserDefaults.standardUserDefaults().setBool(true, forKey: "key")

otherwise it's problematic and you have to do workarounds, like storing the Bool in NSNumber or String .

Answer 2

You said in the comment that you've got an error about "finding nil", but it's not really the same as an error about "Can't assign Bool to AnyObject"...

For your nil error, you have to replace those forced typecasts:

category["name"] as! String

with optional binding:

if let name = category["name"] as? String {

}

Now it will fail but not crash if a property is nil, and will properly append to the array of dictionaries:

let category = ["name":"me", "selected":true]

var categorys: [[String:Bool]] = []

if let name = category["name"] as? String, let selected = category["selected"] as? Bool {
    categorys.append([name:selected])
} else {
    // oops, a value was nil, handle the error
}

Same for your other operations, don't use forced casts:

if let myBool = self.categorys[indexPath.row]["selected"] where myBool == true {
    self.categorys[indexPath.row]["selected"] = false
}

And since self.categorys[indexPath.row]["selected"] is a Bool type, don't assign a string like "false" but the actual false value.