#chapter 4

#1 Optional: let x:String? = nil let x = Optional.None let y:String? = "hello" let y = Optional.Some("hello") var z = x! switch x { case Some(let value): y = x case None: //raise an exception } #2 Array: var a = Array() //equals to var a = String

	let animals = [""]
	animals.append("")
	let animal = amimals[1]
	for animal in animals{
	print("\(animal)")
	}

#3 Dictionary: var pac10teamRankings = Dictionary<String, Int>() var pac10teamRankings = String:Int pac10teamRankings = ["a":"1","b":"2"] let ranking = pac10teamRankings["a"]

	for (key,val) in pac10teamRankings{
	print("\(key)=\(value)")
	}

#4 Range: struct Range{ var startIndex: T var endIndex: T }

	let array = ["a","b","c","d"]
	let sub1 = array[2...3]
	let sub2 = array[2..<3]
	for i in [27...104]{}

#5 NSObject ##base class for all Objective-C classes #6 NSNumber let n = NSNumber(35.5) let intrusion = n.intValue //also cane doubleValue,boolValue,etc

#7 NSDate #8 NSData #9 Data Structures in Swift class struct enum Inheritance(class only)