CODEWITHSUNDEEP
swiftnsmutablearray
Salih Ç
Salih Ç

Reputation: 38

Mutating method sent to immutable object error with mutableCopy()

In short after getting arrays from NSUserDefaults I'm getting Mutating method sent to immutable object error when I'm trying to change NSMutableArray value;

generalDone[self.todoTableView.selectedRow] = 1

When saving to NSUserDefaults I'm adding all NSMutableArrays to one NSMutableArray. Like;

var saveArray:NSMutableArray = NSMutableArray()
saveArray.removeAllObjects()
saveArray.add(generalTodos)
..
..
..
saveArray.add(generalDone)
UserDefaults.standard.set(saveArray, forKey: "test3")

But when I'm getting arrays from NSUserDefault I'm sure it is a mutableCopy(). 

if UserDefaults.standard.value(forKey: "test3") != nil {
    saveArray = UserDefaults.standard.mutableArrayValue(forKey: "test3").mutableCopy() as! NSMutableArray

    generalTodos = saveArray[0] as! NSMutableArray
    generalDone = saveArray[1] as! NSMutableArray
}

Still getting same error. Maybe silly idea but I'm thinking arrays in saveArrays still not mutable. But don't know how to manage them. What's your ideas?

Trying to learn swift. Please be polite. -_-

Upvotes: 0

Views: 210

Answers (1)

matt
matt

Reputation: 534950

If you are going to use Objective-C NSMutableArray, saying as! NSMutableArray won't make one; the way to make an NSMutableArray is to say 

let mutableArray = NSMutableArray(array: otherArray)

But you should be using Swift arrays, not Objective-C NSArray/NSMutableArray. To make a Swift array mutable, declare it with var, not let. For example, if generalTodos is an array of strings, you could say

var generalTodos = [String]()

Upvotes: 1

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