Swift 3:- For Loops, While Statements, Random Number, Casting & Dictionaries

These are formatted so you can copy the code straight into your Swift Playground files.

// would print up to 9

for i in 0 ..< 10 {

    print (i) //i will increment up one with each iteration of the for loop

}

// would print up to 10

for i in 0 ... 10 {

    print (i)

}

// iterate through an array

let names = ["Bob", "Carl", "Joe", "Dory" ]

for name in names {

    print (name)

}

// nodes in a sprite kit scene (won't work in Playgrounds)

for node in self.children {

    if (node.name == "Ball") {

        //do something

    }

}

While Statements

// The code would run this loop 100 times

var i:Int = 0

while i < 100 {

    print(i)

    i += 1 //increment i so eventually we break out of the while loop

}

// while loops can also be used with non-numbers

var title:String = ""

//this loop will run 5 times

while title != "aaaaa" {

    title = title + "a"  //add another "a" each loop to the title

}

Random Number

//  Make a variable equal to a random number....

let randomNum:UInt32 = arc4random_uniform(100) // range is 0 to 99

// convert the UInt32 to some other  types

let randomTime:TimeInterval = TimeInterval(randomNum)

let someInt:Int = Int(randomNum)

let someString:String = String(randomNum) //string works too

Casting

//  Casting ensures that the value is a particular type var someArray = [AnyObject]() //this array could contain any type of object someArray.append("CartoonSmart.com") //adding a string type to the array //test to see if the first object in the array is actually string if let greatTutorialSite:String = someArray[0] as? String {     //Casting success, the value in the array is a string     print ( "  \(greatTutorialSite) is a great video tutorial site") } // casting is especially important in SpriteKit when we check if nodes // are a particular class, for example: Player, Enemy, Platform etc.

Dictionaries

//create the Swift 3 Dictionary with nothing, and set the types 

// (String will be Key, and any object will be the value

var someDict = [String : AnyObject]()

// add a key and value

someDict["Ex wives"] = 5

print (someDict)

// add another key and value

someDict["Current wives"] = 1

print (someDict)

//remove Current wives. Oh well.

someDict.removeValue(forKey: "Current wives")

print (someDict)

//changes ex wives to 6

someDict["Ex wives"] = 6

print (someDict)

// remove all

someDict.removeAll()

reference :- http://swift3tutorials.com/