How to Create a Nsmutabledictionary in Swift

How to create NSMutableDictionary in swift 2.0

Simply by opening NSMutableDictionary or NSDictionary class interfaces from Xcode 7, you could easily see that the underlying type is actually [NSObject: AnyObject]. It means that the value can't be nil.

Unwrapping text values like txtEmail.text! or txtPassword.text! might look ok and help you to get rid of the compiling error, but it's a bad choice because technically text property of UITextField is optional and your app can crash in that case!

Do this for your safety:

let dictParams: NSMutableDictionary? = ["test" : "test", 
    "username" : txtEmail.text ?? "", // Always use optional values carefully!
    "password" : txtPassword.text ?? "",
    "version" : "1.0", 
    "appId" : "1", 
    "deviceId" : "fasdfasdfrqwe2345sdgdfe56gsdfgsdfg"
]

By the way, in case it's not critical to use NSMutableDictionary, please consider using Swift dictionary like this:

var mutableDictionary = [String: AnyObject] 

// OR this if the value can be nil
var mutableDictionary = [String: AnyObject?] 

How to add field to NSMutableDictionary Swift

Use Dictionary in swift instead of NSDictionary. Also, you need to give the type while declaring the Dictionary variable.

Try this:

var villages = [[String : Any]]()
var bars = [[String : Any]]()
var allBars = [[String : Any]]()

//And this
bars[2]["Distance"] = distanceInMiles

bars[2] in the above code will only work if the array bars has atleast 3 elements in it. Otherwise it will give "Array index out of bounds" exception.

Swift Dictionary [String:String] to NSMutableDictionary?

There’s no built-in cast for this. But instead you can use NSMutableDictionary’s initializer that takes a dictionary:

var foundationDictionary = NSMutableDictionary(dictionary: dictionary)

How to add NSMutableDictionary values in NSMutableArray

If your arrVideoRange is NSMutableArray like this

var arrVideoRange : NSMutableArray = []

then try this

for value in videoRangeDic.allValues{

    arrVideoRange.addObjects(from: value as [Any])

}

Swift equivalent to `[NSDictionary initWithObjects: forKeys:]`

As of Swift 4 you can create a dictionary directly from a
sequence of key/value pairs:

let keys = ["one", "two", "three"]
let values = [1, 2, 3]

let dict = Dictionary(uniqueKeysWithValues: zip(keys, values))

print(dict) // ["one": 1, "three": 3, "two": 2]

This assumes that all keys are different, otherwise it will abort
with a runtime exception.

If the keys are not guaranteed to be distinct then you can do

let keys = ["one", "two", "one"]
let values = [1, 2, 3]

let dict = Dictionary(zip(keys, values), uniquingKeysWith: { $1 })

print(dict) // ["one": 3, "two": 2]

The second argument is a closure which determines which value "wins"
in the case of duplicate keys.

Swift - Append to NSMutableDictionary

Yes you are actually replacing the RSVPDirectory[firstLetter], overriding it every time with new tmp.

What you are looking for is this:

//RSVPDirectory[firstLetter] = tmp //Replace this line with below code
let tempArray = RSVPDirectory[firstLetter] as? [AnyHashable]
tempArray?.append(tmp)
RSVPDirectory[firstLetter] = tmpArray

Here I have used a tempArray because we want to mutate the array. Accessing it directly and trying to append new value will in-turn try to mutate an immutable value. So first I have got the array in the tempArray and then after mutating the array I swapped it back in the dictionary with updated values.

How to create and access a NSDictionary in Swift

The issue is actually that a subscript lookup for a Dictionary in Swift returns an optional value:

This is a pretty great feature - you can't be guaranteed that the key you're looking for necessarily corresponds to a value. So Swift makes sure you know that you might not get a value from your lookup.

This differs a little bit from subscript behavior for an Array, which will always return a value. This is a semantically-driven decision - it's common in languages for dictionary lookups to return null if there is no key - but if you try to access an array index that does not exist (because it's out of bounds), an exception will be thrown. This is how Swift guarantees you'll get a value back from an array subscript: Either you'll get one, or you'll have to catch an exception. Dictionaries are a little more lenient - they're "used to" not having the value you're asking for.

As a result, you can use optional binding to only use the item if it actually has a value, like so:

if let theArray = dictionary["MainString1"] {
    let item0 = theArray[0]
} else {
    NSLog("There was no value for key 'MainString1'")
}

swift: Add multiple key, value objects to NSDictionary

You can definitely make a dictionary of dictionaries. However, you need a different syntax for that:

var myDictOfDict:NSDictionary = [
    "a" : ["fname": "abc", "lname": "def"]
,   "b" : ["fname": "ghi", "lname": "jkl"]
,   ... : ...
]

What you have looks like an array of dictionaries, though:

var myArrayOfDict: NSArray = [
    ["fname": "abc", "lname": "def"]
,   ["fname": "ghi", "lname": "jkl"]
,   ...
]

To get JSON that looks like this

{"Data": [{"User": myDict1}, {"User": myDict1},...]}

you need to add the above array to a dictionary, like this:

var myDict:NSDictionary = ["Data" : myArrayOfDict]

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