[Swift]Scanner字符串扫描类

Scanner字符串扫描类：

1.Scanner继承自NSObject，遵守NSCopying协议。是一个用于扫描指定字符串的抽象类。

2.可以创建Scanner时制定他的String属性，然后scanner会按照你的要求从头到尾扫描这个字符串的每个字符。

3.扫描操作从上次扫描的位置开始，并且继续往后扫描直到指定的内容出现为止（如果有的话）。

一、部分属性详解

 1 //(只读)返回当前被扫描的字符串
 2 open var string: String { get }
 3 
 4 //当前扫描的位置，默认是从0开始的。通过设置这个属性值，可以自定义扫描的位置
 5 open var scanLocation: Int
 6 
 7 //这个集合是用来设置我们需要跳过扫描的一个字符集合
 8 open var charactersToBeSkipped: CharacterSet?
 9 
10 //是否大小写敏感
11 open var caseSensitive: Bool
12 
13 //用给定扫描字符串初始化
14 public init(string: String)

二、部分方法详解

2.10、方法内容：

（1）扫描该类型的字符串,并将扫描结果赋值给result

（2）判断该字符串的第一个字符(默认第一个,可根据scanLocation属性设置)是否为该类型

 1 open func scanInt32(_ result: UnsafeMutablePointer<Int32>?) -> Bool
 2 
 3 @available(iOS 2.0, *)
 4 open func scanInt(_ result: UnsafeMutablePointer<Int>?) -> Bool
 5 
 6 open func scanInt64(_ result: UnsafeMutablePointer<Int64>?) -> Bool
 7 
 8 @available(iOS 7.0, *)
 9 open func scanUnsignedLongLong(_ result: UnsafeMutablePointer<UInt64>?) -> Bool
10 
11 open func scanFloat(_ result: UnsafeMutablePointer<Float>?) -> Bool
12 
13 open func scanDouble(_ result: UnsafeMutablePointer<Double>?) -> Bool

2.11、示例：只包含数字的字符串

 1 var intType:Int = 0
 2 var int64Type:Int64 = 0
 3 var int32Type:Int32 = 0
 4 var floatType:Float = 0.0
 5 var doubleType:Double = 0.0
 6 //判断字符串包含的类型(输出结果为true)
 7 print(Scanner(string: "123456789").scanInt(&intType))
 8 print(Scanner(string: "123456789").scanInt64(&int64Type))
 9 print(Scanner(string: "123456789").scanInt32(&int32Type))
10 print(Scanner(string: "123456789.99").scanFloat(&floatType))
11 print(Scanner(string: "123456789.99").scanDouble(&doubleType))
12 //Print
13 /*
14 true
15 true
16 true
17 true
18 true
19 */

2.12、示例：包含非数字的字符串

 1 var intType: Int = 0
 2 let scanner = Scanner(string: "a1b2c3d4")
 3 scanner.scanLocation = 1
 4 print(scanner.scanInt(&intType)) 
 5 //Print true
 6 
 7 var doubleType: Double = 0.0
 8 let scanner1 = Scanner(string: "a1b2.5c3d4")
 9 scanner1.scanLocation = 0
10 print(scanner1.scanDouble(&doubleType))
11 //Print false

2.20、方法内容：

（1）扫描字符串前缀是否是"0x"或者"0X",返回true或false.
（2）将0x(0X)字符后面符合十六进制数的字符串转化成十进制数(可运用到UIColor关于十六进制数的转化)。

 1 // Optionally prefixed with "0x" or "0X"
 2 open func scanHexInt32(_ result: UnsafeMutablePointer<UInt32>?) -> Bool
 3 
 4 @available(iOS 2.0, *)
 5 // Optionally prefixed with "0x" or "0X"
 6 open func scanHexInt64(_ result: UnsafeMutablePointer<UInt64>?) -> Bool
 7 
 8 @available(iOS 2.0, *)
 9 // Corresponding to %a or %A formatting. Requires "0x" or "0X" prefix.
10 open func scanHexFloat(_ result: UnsafeMutablePointer<Float>?) -> Bool
11 
12 @available(iOS 2.0, *)
13 // Corresponding to %a or %A formatting. Requires "0x" or "0X" prefix.
14 open func scanHexDouble(_ result: UnsafeMutablePointer<Double>?) -> Bool

2.21、示例：

 1 var uint32Type:UInt32 = 0
 2 var uint64Type:UInt64 = 0
 3 
 4 print(Scanner(string: "0xab").scanHexInt32(&uint32Type))
 5 //Print true
 6 print(uint32Type)
 7 //Print 171
 8 print(Scanner(string: "xcd").scanHexInt64(&uint64Type))
 9 //Print false
10 print(Scanner(string: "0xcd").scanHexInt64(&uint64Type))
11 //Print true
12 print(uint64Type) 
13 //Print 205

2.30、从字符串中找出给定字符的所在位置

open func scanString(_ string: String, into result: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool

2.31、示例代码

 1 //声明一个字符串变量，为可选类型
 2 var str:String? = String()
 3 //初始化一个字符串扫描对象
 4 let scan = Scanner(string: "strengthen")
 5 //判断是否扫描到字符串的末尾
 6 while !scan.isAtEnd
 7 {  
 8     //扫描位置加1
 9     scan.scanLocation += 1
10     //输出扫描位置
11     print(scan.scanLocation)
12     //从字符串中找出给定字符的所在位置
13     scan.scanString("n", into: &str)
14     //输出字符串，注意str为可选类型
15     print(str)
16     //重新初始化
17     str = String()
18 }
19 //Print
20 /*
21 1
22 Optional("")
23 2
24 Optional("")
25 3
26 Optional("")
27 4
28 Optional("n")
29 6
30 Optional("")
31 7
32 Optional("")
33 8
34 Optional("")
35 9
36 Optional("n")
37 */

2.4、Scanner的其他方法

1 //从scan中扫描出string放入result中，如果不需要存储string，则result传NULL
2 open func scanCharacters(from set: CharacterSet, into result: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool
3 
4 //从scan中扫描出string之外的数据放入result中，如果不需要存储string，则result传NULL
5 open func scanUpTo(_ string: String, into result: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool
6 
7 //从scan中扫描出set之外的数据放入result中，如果不需要存储string，则result传NULL
8 open func scanUpToCharacters(from set: CharacterSet, into result: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool

2.5、使用Scanner处理UIColor十六进制数值：在UIColor的extension中添加扩展方法

 1 /* 十六进制颜色扩展*/
 2 convenience init?(hex : String, alpha : CGFloat = 1.0) {
 3     //1.判断字符串长度是否符合
 4     guard hex.characters.count >= 6 else {
 5         return nil
 6     }
 7     //2.将字符串转成大写
 8     var tempHex = hex.uppercased()
 9     //3.判断开头
10     if tempHex.hasPrefix("0x") || tempHex.hasPrefix("##") || tempHex.hasPrefix("0X") {
11         //去掉开头
12         tempHex = tempHex.dropFirst(2)
13     }
14     if tempHex.hasPrefix("#") {
15         tempHex = tempHex.dropFirst()
16     }
17     //4.分别截取RGB
18     var range = NSRange(location: 0, length: 2)
19     let rHex = (tempHex as NSString).substring(with: range)
20     range.location = 2
21     let gHex = (tempHex as NSString).substring(with: range)
22         range.location = 4
23     let bHex = (tempHex as NSString).substring(with: range)
24     //5.将字符串转化成数字  emoji也是十六进制表示(此处也可用Float类型)
25     var r : UInt32 = 0, g : UInt32 = 0, b : UInt32 = 0
26     //创建扫描器,将字符串的扫描结果赋值给:r,g,b
27     Scanner(string: rHex).scanHexInt32(&r)
28     Scanner(string: gHex).scanHexInt32(&g)
29     Scanner(string: bHex).scanHexInt32(&b)
30     
31     self.init(r : CGFloat(r), g : CGFloat(g), b : CGFloat(b))
32 }
33 
34 /*RGB三原色*/
35 convenience init(r : CGFloat, g : CGFloat, b : CGFloat, alpha : CGFloat = 1.0) {
36     self.init(red: r / 255.0, green: g / 255.0, blue: b / 255.0, alpha: alpha)
37 }