--- /dev/null
+//: Playground - noun: a place where people can play
+
+import UIKit
+
+var str = "Hello, playground.小狗:🐶 锤子:🔨"
+
+
+func printLine(title: String) -> Void {
+ let line = String(format:"[%@]-----------------------------------", title)
+ print(line)
+}
+
+// Index
+var strInx:String.Index = str.startIndex
+strInx.successor()
+print(strInx)
+
+for c in str.characters {
+ print(c, terminator: "")
+}
+print()
+
+// Print separator & terminator
+var company:Array<String> = [ "Apple", "Google", "Facebook", "Tencent" ]
+print(company, separator: "#", terminator: " $$$$$\n")
+
+printLine("Count company Array 1")
+for (i,v) in company.enumerate() {
+ print(i, v, separator: " - ", terminator: "\n")
+}
+
+printLine("Count company Array 2")
+company.insert("Alibaba", atIndex: company.count)
+for i in 0..<company.count {
+ print(i, company[i], separator: " - ")
+}
+company.removeLast()
+
+var someIntsA: [Int] = []
+var someIntsB = [Int]()
+var someIntsC = [Int](count: 10, repeatedValue: 1)
+someIntsA.append(1)
+someIntsB.replaceRange(Range<Int>(0..<someIntsB.count), with: [1,3,4])
+someIntsC.removeAtIndex(4)
+