- Countable Range
闭区间和半开半闭区间
let closedRange = 0...5
//012345
for i in closedRange {
print(i)
}
let halfOpenRange = 0..<5
//01234
for i in halfOpenRange {
print(i)
}
- 不需要循环常数
不需要使用循环索引时，可以用下划线替代
sum = 1
var lastSum = 0
for _ in 0..<count {
let temp = sum
sum = sum + lastSum
lastSum = temp
}
- 指定条件的loop
使用where关键字
sum = 0
for i in 1...count where i % 2 == 1 {
sum += 1
}
- case语法
- 多case情况
let hourOfDay = 12
let timeOfDay: String
switch hourOfDay {
case 0, 1, 2, 3, 4, 5:
timeOfDay = "Early morning"
case 6, 7, 8, 9, 10, 11:
timeOfDay = "Morning"
case 12, 13, 14, 15, 16:
timeOfDay = "Afternoon"
case 17, 18, 19:
timeOfDay = "Evening"
case 20, 21, 22, 23:
timeOfDay = "Late evening"
default:
timeOfDay = "INVALID HOUR!"
}
print(timeOfDay)
- ranges应用在case
switch hourOfDay {
case 0...5:
timeOfDay = "Early morning"
case 6...11:
timeOfDay = "Morning"
case 12...16:
timeOfDay = "Afternoon"
case 17...19:
timeOfDay = "Evening"
case 20..<24:
timeOfDay = "Late evening"
default:
timeOfDay = "INVALID HOUR!"
}
- 条件语法结合case使用
switch number {
case let x where x % 2 == 0:
print("Even")
default:
print("Odd")
}
省略常数x
switch number {
case _ where number % 2 == 0:
print("Even")
default:
print("Odd")
}
- 部分匹配（Partial matching）
let coordinates = (x: 3, y: 2, z: 5)
switch coordinates {
case (0, 0, 0): // 1
print("Origin")
case (_, 0, 0): // 2
print("On the x-axis.")
case (0, _, 0): // 3
print("On the y-axis.")
case (0, 0, _): // 4
print("On the z-axis.")
default: // 5
print("Somewhere in space")
}
switch coordinates {
case (0, 0, 0):
print("Origin")
case (let x, 0, 0):
print("On the x-axis at x = \(x)")
case (0, let y, 0):
print("On the y-axis at y = \(y)")
case (0, 0, let z):
print("On the z-axis at z = \(z)")
case let (x, y, z):
print("Somewhere in space at x = \(x), y = \(y), z = \(z)")
}
switch coordinates {
case let (x, y, _) where y == x:
print("Along the y = x line.")
case let (x, y, _) where y == x * x:
print("Along the y = x^2 line.")
default:
break
}
