判斷
if...
else if ...
else...
switch
guard ... else
迴圈
(明確知道要執行的次數）
for in
(不知道要執行的次數）
while
(不知道要執行的次數）
repead
while
let names = ["Anna", "Alex", "Brian", "Jack"];
for name in names {
print("Hello!\(name)");
}
let numberOfLegs = ["spider":8, "ant":6, "cat":4];
for (animalName, legCount) in numberOfLegs {
print("\(animalName)s have \(legCount) legs");
}
for index in 1..<5{
print(index);
}
let base = 3;
let power = 10;
var answer = 1;
for _ in 1...power {
answer *= base;
}
let minutes = 60
let minuteInterval = 5
//從0開始，每次＋5，到60（不包含60）
for tickMark in stride(from: 0, to: minutes, by: minuteInterval) {
print(tickMark);
}
//從0開始，每次＋5，到60（包含60）
for tickMark in stride(from: 0, through: minutes, by: minuteInterval) {
print(tickMark);
}
while 判斷 {
}
//相當於C的for(int i=25,i>=0;i--)
var finalSquare = 25
while finalSquare >=0 {
print(finalSquare);
finalSquare -= 1;
}
finalSquare = 25;
repeat {
finalSquare -= 1;
} while finalSquare >=0
單向式
if 判斷式 {
}
雙向式 （一定執行其中一個）
if 判斷式 {
} else {
}
多向式（一定執行其中一個）
if 判斷式 {
} else if 判斷式{
} else if 判斷式{
} else {
}
var temperatureInFahrenheit = 30;
if temperatureInFahrenheit <= 32 {
print("非常冷");
}
temperatureInFahrenheit = 35;
if temperatureInFahrenheit <= 32 {
print("非常冷");
} else {
print("不會冷");
}
temperatureInFahrenheit = 90;
if temperatureInFahrenheit <= 32 {
print("非常冷");
} else if temperatureInFahrenheit >= 86{
print("非常熱");
} else {
print("舒適！")
}
//siwft的switch只會執行其中一個區段，執行完跳出switch！
let someCharacter:Character = "z";
switch someCharacter {
case "a":
print("a");
case "z":
print("z");
default:
print("b~y");
}
let anotherCharacter:Character = "a";
switch anotherCharacter {
case "a","A":
print("a,A");
case "b","B":
print("b,B");
default:
print("其他");
}
//interval Matching
let approximateCount = 62
switch approximateCount {
case 0:
print("0");
case 1..<5:
print("1~4");
case 5..<12:
print("5..11");
case 12..<100:
print("12..99");
case 100..<1000;
print("100..999");
default:
print(">1000");
}
//範圍多值比對
let somePoint = (x:1,y:1);
switch somePoint {
case (0,0):
print("0,0");
case (_,0):
print("y=0");
case (0,_):
print("x=0");
case (-2...2,-2...2):
print("-2...2,-2...2");
default:
print("其他");
}
//switch value binding
let anotherPoint = (2,0);
switch anotherPoint {
case (let x, 0):
print("y是0，x是\(x)");
case (0, let y):
print("x是0，y是\(y)");
case let (x, y):
print("x是\(x)，y是\(y)");
//因為一定會執行上方三個區塊其中一個，所以default可以省略！
/*
default:
break;
*/
}
//switch value binding + where
let yetAnotherPoint = (1, -1);
switch yetAnotherPoint {
//where 後面一定接bool
case let (x, y) where x == y:
print("x==y");
case let (x, y) where x == -y:
print("x==-y");
case let (x, y):
print("x=\(x), y=\(y)");
}
提早離開function
guard ... else，只執行false區段，true時不動作！
guard (false) else {
false 區段
}
//guard else
func greet(person:[String:String]) {
guard let name = person["name"] else {
print("key沒有name");
return;
}
print("Hello!\(name)!");
gurade let location = person["location"] else {
print("key沒有location");
return;
}
print("name=\(name),location=\(location)");
}
greet(person: ["name":"John", "location":"Cupertino"]);
