流程控制

SwiftStudy.playground/Pages/03 流程控制.xcplaygroundpage/Contents.swift

@@ -0,0 +1,190 @@
+//: [Previous](@previous)
+
+//: ## 区间运算符
+
+//: ### 闭区间运算符
+/*:
+    闭区间运算符：
+        a...b : a <= 取值 <= b
+ */
+
+let names = ["Anna", "Alex", "Brian", "Jack"]
+for i in 0...3 {
+    print(names[i])
+}
+
+let a = 1
+var b = 3
+for i in a...b {
+    print(names[i])
+}
+
+let range = 1...3
+for i in range {
+    print(names[i])
+}
+
+
+
+// i默认是let，有时需要声明为var
+for var i in 1...3 {
+    // i的值可以发生变化
+    i += 5
+    print(i)
+}
+
+// 用不上变量,可以用_进行忽略
+for _ in 1...3 {
+    print("123456")
+}
+
+//: ### 半开区间运算符
+/*:
+    半开区间运算符
+        a..<b : a <= 取值 < b
+ */
+
+ 
+//: ### 单侧区间运算符
+/*:
+    单侧区间运算符
+        a... : a <= 取值
+        ...b : 取值 <= b
+ */
+
+
+//: ### 区间类型
+// 闭区间 ClosedRange
+let range1: ClosedRange<Int> = 1...3
+// 半开区间 Range
+let range2: Range<Int> = 1..<3
+// 单侧区间 PartialRangeThrough
+let range3: PartialRangeThrough<Int> = ...5
+
+
+//: ### 带间隔的区间值
+// 使用函数stride
+for tickMark in stride(from: 4, to: 11, by: 2) {
+    print(tickMark)
+}
+
+
+//: ## switch
+/*:
+    switch注意点
+    - switch必须保证能处理所有的情况
+    - 能处理所有情况的下，可以省略default
+    - switch 也支持Character、String类型
+    - switch 支持区间匹配以及元组匹配
+ */
+
+// 默认可以不写break，并不会贯穿到后面的条件
+var num = 1
+switch num {
+case 1:
+    print("number is 1")
+case 2:
+    print("number is 2")
+default:
+    print("number is other")
+}
+
+// 使用fallthrough可以实现贯穿效果
+var number = 1
+switch number {
+case 1:
+    print("number is 1")
+    fallthrough
+case 2:
+    print("number is 2")
+default:
+    print("number is other")
+}
+
+//: #### 区间匹配
+let count = 62
+switch count {
+case 0:
+    print("none")
+case 1..<5:
+    print ("a few")
+case 5..<12:
+    print("several")
+case 12..<100:
+    print("dozens of")
+case 100..<1000:
+    print("hundreds of")
+default:
+    print("many")
+} // dozens of
+
+
+
+
+//: #### 元组匹配
+// 可以使用下划线_ 忽略某个值
+let point = (1, 1)
+switch point {
+case (0, 0):
+    print("the origin")
+case (_, 0):
+    print ("on the x-axis")
+case (0, _):
+    print("on the y-axis")
+case (-2...2, -2...2):
+    print("inside the box")
+default:
+    print( "outside of the box")
+}
+
+//: ### 值绑定
+// 必要时 let 可以换为 var
+let point1 = (2, 0)
+switch point1 {
+case (let x, 0):
+    print("on the x-axis with a x value of \(x)")
+case (0, let y):
+    print("on the y-axis with a y value of \(y)")
+case let(x, y):
+    print("somewhere else at (\(x), \(y))")
+}
+
+//: ### where
+// 1. 用在case的后边
+let point2 = (1, -1)
+switch point2 {
+case let(x, y) where x == y:
+    print("on the line x == y")
+case let(x, y) where x == -y:
+    print("on the line x == -y")
+case let(x, y):
+    print("somewhere else at (\(x), \(y))")
+}
+
+//2. 对数据进行过虑
+var numbers = [10, 20, 30, -10, -30]
+var sum = 0
+for num in numbers where num > 0 {
+    sum += num;
+}
+print(sum)
+
+//: ### 标签语句
+// 标签语句是
+//    标签: 代码
+outer: for i in 1...4 {
+    for k in 1...4 {
+        if k == 3 {
+            continue outer
+        }
+        
+        if i == 3 {
+            break outer
+        }
+        
+        print("i == \(i), k == \(k)")
+    }
+}
+
+
+//: [Next](@next)

SwiftStudy.playground/contents.xcplayground

@@ -3,5 +3,6 @@
     <pages>
         <page name='01 注释'/>
         <page name='02 数据类型'/>
+        <page name='03 流程控制'/>
     </pages>
 </playground>