NSScanner继承自NSObject，遵守NSCopying协议。是一个用于扫描字符串的抽象类。学会使用这个类，在做对字符串的处理时还是很有帮助的。尤其是在做一些比如将字符串中的某几个关键字变色等。不过这不是本节的关键，因此不做展开。这个类的作用还是要多靠观察和实践，文中有不对的地方多多包涵。
@property (readonly,copy) NSString *string;
// 返回当前被扫描的字符串
@property NSUInteger scanLocation;
// 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
@property (nullable,copy) NSCharacterSet *charactersToBeSkipped;
// 这个集合是用来设置我们需要跳过扫描的一个字符集合
@property BOOL caseSensitive;
// 是否大小写敏感
@property (nullable,retain) id locale;
// 具体用法不知
给出文档的解释
A scanner’s locale affects the way it interprets numeric values from the string. In particular, a scanner uses the locale’s decimal separator to distinguish the integer and fractional parts of floating-point representations. A scanner with no locale set uses non-localized values. New scanners have no locale by default.
- (instancetype)initWithString:(NSString *)string;
// 指定的扫描器初始化方法，用给定扫描字符串初始化
- (BOOL)scanInt:(nullableint *)result;
// 判断给定扫描的字符串的int值是不是整型
NSString *scanString = @"123";
int i;
[scanner scanInt:&i]; // 返回YES
- (BOOL)scanInteger:(nullableNSInteger *)result;
// 与上面的方法相同，就是输入的参数类型不同
- (BOOL)scanLongLong:(nullablelong long *)result;
// 扫描长长整型
- (BOOL)scanUnsignedLongLong:(nullableunsigned longlong *)result;
// 扫描无符号的长长整型
- (BOOL)scanFloat:(nullablefloat *)result;
// 扫描float型的数据
NSString *scanString = @"123";
float f;
[scanner scanFloat:&f]; // 返回NO
- (BOOL)scanDouble:(nullabledouble *)result;
// 扫描double类型的数据
- (BOOL)scanHexInt:(nullableunsigned *)result; // Optionally prefixed with "0x" or "0X"
- (BOOL)scanHexLongLong:(nullableunsigned longlong *)result; // Optionally prefixed with "0x" or "0X"
- (BOOL)scanHexFloat:(nullablefloat *)result; // Corresponding to %a or %A formatting. Requires "0x" or "0X" prefix.
- (BOOL)scanHexDouble:(nullabledouble *)result; // Corresponding to %a or %A formatting. Requires "0x" or "0X" prefix.
// 扫描前缀是否带有0x或者0X
NSString *scanString = @"0x1";
NSScanner *scanner = [NSScanner scannerWithString:scanString];
unsigned r;
[scanner scanHexInt:&r]; // 返回YES
- (BOOL)scanString:(NSString *)string intoString:(NSString *__nullable * __nullable)result;
// 给定一个字符串，从扫描的字符串中找出相同的
NSString *scanString = @"897岁k";
NSScanner *scanner = [NSScanner scannerWithString:scanString];
NSString *availdStr;
while (!scanner.isAtEnd) {
scanner.scanLocation++;
NSLog(@"%ld",scanner.scanLocation);
[scanner scanString:@"k"intoString:&availdStr];
if (availdStr) {
NSLog(@"%@",availdStr);
}
}
输出：
2016-05-24 20:15:42.571 NSScanner[5391:383531] 1
2016-05-24 20:15:42.572 NSScanner[5391:383531] 2
2016-05-24 20:15:42.572 NSScanner[5391:383531] 3
2016-05-24 20:15:42.572 NSScanner[5391:383531] 4
2016-05-24 20:15:42.572 NSScanner[5391:383531] k
- (BOOL)scanCharactersFromSet:(NSCharacterSet *)set intoString:(NSString *__nullable * __nullable)result;
// 扫描出给定字符集合中的字符放入到value中，只要是set集合中有的字符或字符串都会被扫描出来，直到下一个扫描空缺。
NSString *scanString = @"897岁kGs5a--@家 1k12&&＊） l12";
NSScanner *scanner = [NSScanner scannerWithString:scanString];
NSString *availdStr;
while (!scanner.isAtEnd) {
scanner.scanLocation++;
[scanner scanCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"kG125"]intoString:&availdStr];
if (availdStr) {
NSLog(@"%@",availdStr);
}
}
输出：
2016-05-24 20:20:33.180 NSScanner[5435:388398] kG
2016-05-24 20:20:33.181 NSScanner[5435:388398] 5
2016-05-24 20:20:33.181 NSScanner[5435:388398] 5
2016-05-24 20:20:33.181 NSScanner[5435:388398] 5
2016-05-24 20:20:33.181 NSScanner[5435:388398] 5
2016-05-24 20:20:33.182 NSScanner[5435:388398] 5
2016-05-24 20:20:33.182 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.182 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.182 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.182 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.182 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.183 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.183 NSScanner[5435:388398] 1k12
2016-05-24 20:20:33.183 NSScanner[5435:388398] 12
- (BOOL)scanUpToString:(NSString *)string intoString:(NSString *__nullable * __nullable)result;
// 扫描到给定的字符串后，将从一开始扫描位开始的地方开始截取,并且去掉指定的string(第一个参数);或者是到扫描结束，将字符串末尾往前直到碰到--为止的字符串截取下来。
NSString *scanString = @"897岁kGs5a--@家--1k12&&＊） l12";
NSScanner *scanner = [NSScanner scannerWithString:scanString];
scanner.scanLocation = 3;
NSString *availdStr;
while (!scanner.isAtEnd) {
scanner.scanLocation++;
[scanner scanUpToString:@"-"intoString:&availdStr];
if (availdStr) {
NSLog(@"%@",availdStr);
}
}
输出：
2016-05-24 20:33:04.318 NSScanner[5600:402085] kGs5a
2016-05-24 20:33:04.319 NSScanner[5600:402085] kGs5a
2016-05-24 20:33:04.320 NSScanner[5600:402085] @家
2016-05-24 20:33:04.320 NSScanner[5600:402085] @家
2016-05-24 20:33:04.321 NSScanner[5600:402085] 1k12&&＊） l12
- (BOOL)scanUpToCharactersFromSet:(NSCharacterSet *)set intoString:(NSString *__nullable * __nullable)result;
// 扫到给定集合，原理与上一条相同
+ (instancetype)scannerWithString:(NSString *)string;
// 类方法创建
+ (id)localizedScannerWithString:(NSString *)string;
// 不是很明白
给出文档的解释
Returns an NSScanner object that scans a given string according to the user’s default locale.
An NSScanner object that scans aString according to the user’s default locale.