diff --git a/source/chapter3/07_Patterns.md b/source/chapter3/07_Patterns.md
index b9fcb902..28e2a23a 100755
--- a/source/chapter3/07_Patterns.md
+++ b/source/chapter3/07_Patterns.md
@@ -11,6 +11,7 @@
- [值绑定模式(Value-Binding Pattern)](#value-binding_pattern)
- [元组模式(Tuple Pattern)](#tuple_pattern)
- [枚举用例模式(Enumeration Case Pattern)](#enumeration_case_pattern)
+- [可选模式(Optional Patterns)](#optional_patterns)
- [类型转换模式(Type-Casting Patterns)](#type-casting_patterns)
- [表达式模式(Expression Pattern)](#expression_pattern)
@@ -18,20 +19,17 @@
swift中有2个基本的模式种类:一类能成功和任何值的类型相匹配,另一类在运行时(runtime)和某特定值匹配时可能会失败。
-第一类模式用于析构简单变量,常量和可选绑定中的值。此类模式包括通配符模式,标识符模式,以及任何包含了它们的值绑定模式或者元祖模式。你可以为这些模式指定一个类型注释(type annotation)来限制它们只能匹配某种特定类型的值。
+第一类模式用于解构简单变量,常量和可选绑定中的值。此类模式包括通配符模式(wildcard pattern),标识符模式(identifier pattern),以及任何包含了它们的值绑定模式(value binding pattern)或者元祖模式(tuple pattern)。你可以为这类模式指定一个类型注释(type annotation)来限制它们只能匹配某种特定类型的值。
第二类模式用于全模式匹配,这种情况下你用来相比较的值在运行时可能还不存在。此类模式包括枚举用例模式,可选模式,表达式模式和类型转换模式。你在`switch`语句的case标签中,`do`语句的`catch`从句中,或者在`if, while, guard`和`for-in`语句的case条件句中使用这类模式。
-在Swift中,模式出现在变量和常量的声明(在它们的左侧),`for-in`语句和`switch`语句(在它们的case标签)中。尽管任何模式都可以出现在`switch`语句的case标签中,但在其他情况下,只有通配符模式(wildcard pattern),标识符模式(identifier pattern)和包含这两种模式的模式才能出现。
-
-你可以为通配符模式(wildcard pattern),标识符模式(identifier pattern)和元组模式(tuple pattern)指定类型注释,用来限制这种模式只匹配某种类型的值。
-
> 模式(Patterns) 语法
> *模式* → [*通配符模式*](..\chapter3\07_Patterns.html#wildcard_pattern) [*类型注解*](..\chapter3\03_Types.html#type_annotation) _可选_
> *模式* → [*标识符模式*](..\chapter3\07_Patterns.html#identifier_pattern) [*类型注解*](..\chapter3\03_Types.html#type_annotati(Value Binding)on) _可选_
> *模式* → [*值绑定模式*](..\chapter3\07_Patterns.html#value_binding_pattern)
> *模式* → [*元组模式*](..\chapter3\07_Patterns.html#tuple_pattern) [*类型注解*](..\chapter3\03_Types.html#type_annotation) _可选_
> *模式* → [*enum-case-pattern*](..\chapter3\07_Patterns.html#enum_case_pattern)
+> *模式* → [*可选模式*](..\chapter3\07_Patterns.html#optional_pattern) [*类型注解*](..\chapter3\03_Types.html#optional_type) _可选_
> *模式* → [*type-casting-pattern*](..\chapter3\07_Patterns.html#type_casting_pattern)
> *模式* → [*表达式模式*](..\chapter3\07_Patterns.html#expression_pattern)
@@ -42,7 +40,7 @@ swift中有2个基本的模式种类:一类能成功和任何值的类型相
```swift
for _ in 1...3 {
- // Do something three times.
+// Do something three times.
}
```
@@ -75,9 +73,9 @@ let someValue = 42
```swift
let point = (3, 2)
switch point {
- // Bind x and y to the elements of point.
+// Bind x and y to the elements of point.
case let (x, y):
- println("The point is at (\(x), \(y)).")
+println("The point is at (\(x), \(y)).")
}
// prints "The point is at (3, 2).”
```
@@ -100,7 +98,7 @@ case let (x, y):
let points = [(0, 0), (1, 0), (1, 1), (2, 0), (2, 1)]
// This code isn't valid.
for (x, 0) in points {
- /* ... */
+/* ... */
}
```
@@ -127,6 +125,46 @@ let (a): Int = 2 // a: Int = 2
> 枚举用例模式语法
> *enum-case-pattern* → [*类型标识*](..\chapter3\03_Types.html#type_identifier) _可选_ **.** [*枚举的case名*](..\chapter3\05_Declarations.html#enum_case_name) [*元组模式*](..\chapter3\07_Patterns.html#tuple_pattern) _可选_
+
+
+
+## 可选模式(Optional Pattern)
+
+可选模式 封装在一个`Some(T)`
+
+可选模式由一个标识符模式和紧随其后的一个问号组成,在某种情况下表现为枚举用例模式。
+
+由于可选模式是`optionan`和`ImplicitlyUnwrappedOptional`枚举用例模式的语法糖,下面的两种写法一样的:
+
+```swift
+let someOptional: Int? = 42
+// Match using an enumeration case pattern
+if case .Some(let x) = someOptional {
+ print(x)
+}
+
+// Match using an optional pattern
+if case let x? = someOptional {
+ print(x)
+}
+```
+
+可选模式在`for-in`语句提供了在一个元素是可选类型的数组中迭代的简便的方式,只为数组中的非空元素执行循环。
+
+```swift
+let arrayOfOptionalInts: [Int?] = [nil, 2, 3, nil, 5]
+// Match only non-nil values
+for case let number? in arrayOfOptinalInts {
+ print("Found a \(number)")
+}
+//Found a 2
+//Found a 3
+//Found a 5
+
+```
+> 可选模式语法
+> *optional-pattern* → [*类型标识*](..\chapter3\03_Types.html#type_identifier) ?
+
## 类型转换模式(Type-Casting Patterns)
@@ -157,11 +195,11 @@ let (a): Int = 2 // a: Int = 2
let point = (1, 2)
switch point {
case (0, 0):
- println("(0, 0) is at the origin.")
+println("(0, 0) is at the origin.")
case (-2...2, -2...2):
- println("(\(point.0), \(point.1)) is near the origin.")
+println("(\(point.0), \(point.1)) is near the origin.")
default:
- println("The point is at (\(point.0), \(point.1)).")
+println("The point is at (\(point.0), \(point.1)).")
}
// prints "(1, 2) is near the origin.”
```
@@ -171,15 +209,15 @@ default:
```swift
// Overload the ~= operator to match a string with an integer
func ~=(pattern: String, value: Int) -> Bool {
- return pattern == "\(value)"
+return pattern == "\(value)"
}
switch point {
case ("0", "0"):
- println("(0, 0) is at the origin.")
+println("(0, 0) is at the origin.")
case ("-2...2", "-2...2"):
- println("(\(point.0), \(point.1)) is near the origin.")
+println("(\(point.0), \(point.1)) is near the origin.")
default:
- println("The point is at (\(point.0), \(point.1)).")
+println("The point is at (\(point.0), \(point.1)).")
}
// prints "(1, 2) is near the origin.”
```