swift流程控制

let point = (1,1);

switch point {

case (0,0):

print("(0,0) is atthe origin");

case (_,0):

print("(\(point.0),0) is on the X-axis");

case (0,_):

print("(0,\(point) is on the Y-axis)");

case (-2...2,-2...2):

print("(\(point.0),\(point.1))
is inside the box");

default:

print("(\(point.0),\(point.1))
is outside of the box");

}

let point2 = (0,2);

switch point2 {

case (let x,0):

print("on the x-axis with an x value of
\(x)");

case (0,
let y):

print("on the y-axis with a y value of
\(y)");

case (let x,
let y):

print("somewhere else at (\(x),\(y))");

}

//where

let point3 = (1,-1);

switch point3 {

case let (x,y)
where x == y:

print("(\(x),\(y)) is on the line x == y");

case let (x, y)
where x == -y:

print("(\(x),\(y)) is on the line x == -y");

case let (x,y):

print("(\(x),\(y)) is just some arbitrarypoint");

}

//fallthrough

/**

如果需要C语言风格的贯穿特性，可以在每个需要该特性的case分支中使用fallthrough关键字

*/

let integerToDescibe =
5;

var description =
"the number \(integerToDescibe) is";

switch integerToDescibe {

case 2,3,4,5,6,7,11,13,17,19:

description += "a prime number, and also";

// fallthrough

default:

description += " an integer";

}

print(description);

//带标签的语句

/**

通过该语句的关键词的同一行前面放置一个标签，并且该标签后面还需带着一个冒号。

`label name`: while `condition` {

`statements`

}

*/

let finalSquare =
25;

var board = Array<Int>(count: finalSquare +
1, repeatedValue:
0);

board[3] = 8;

board[6] = 11;

board[9] = 9;

board[10] = 2;

board[14] = -10;

board[19] = -11;

board[22] = -2;

board[24] = -8;

var square = 0;

var diceRoll = 0

gameLoop : while square != finalSquare {

if ++diceRoll ==
7 {

diceRoll = 1;

}

switch square + diceRoll {

case finalSquare:

print("到达最后一个方块，游戏结束");

break gameLoop;

case let newSquare
where newSquare > finalSquare:

print("超出最后一个方块，再掷一次");

continue gameLoop;

default:

print("本次移动有效");

square += diceRoll;

square += board[square];

}

}

print("Game over!");