swift where与匹配模式的实例详解

let point = (3,3)
switch point{
case let (x,y) where x == y:
  print("It's on the line x == y!")
case let (x,y) where x == -y:
  print("It's on the line x == -y!")
case let (x,y):
  print("It's just an ordinary point.")
  print("The point is ( \(x) , \(y) )")
}

let age = 19
switch age{
case 10...19:
  print("You're a teenager.")
default:
  print("You're not a teenager.")
}


if case 10...19 = age{
  print("You're a teenager.")
}

if case 10...19 = age where age >= 18{
  print("You're a teenager and in a college!")
}

let vector = (4,0)
if case ( let x , 0 ) = vector where x > 2 && x < 5{
  print("It's the vector!")
}

for i in 1...100{
  if i%3 == 0{
    print(i)
  }
}

for case let i in 1...100 where i % 3 == 0{
  print(i)
}