简介
NSCharacterSet ，以及它的可变类型 NSMutableCharacterSet，用面向对象的方式来表示一组Unicode字符。它经常与NSString及NSScanner组合起来使用，在不同的字符上做过滤、删除或者分割操作。
方法和属性介绍：
NSCharacterSet 中提供的下面属性都是只读的, 且在NSMutableCharacterSet中有一致的类方法
1.controlCharacterSet //控制符的字符集
2.whitespaceCharacterSet //空格的字符集
3.whitespaceAndNewlineCharacterSet //空格和换行符的字符集
4.decimalDigitCharacterSet //十进制数字的字符集
5.letterCharacterSet //字母的字符集
6.lowercaseLetterCharacterSet //小写字母的字符集
7.uppercaseLetterCharacterSet //大写字母的字符集
8.nonBaseCharacterSet //非基础的字符集
9.alphanumericCharacterSet //字母和数字的字符集
10.decomposableCharacterSet //可分解
11.illegalCharacterSet //非法的字符集
12.punctuationCharacterSet //标点的字符集
13.capitalizedLetterCharacterSet //首字母大写的字符集
14.symbolCharacterSet //符号的字符集
15.newlineCharacterSet //换行符的字符集
NSCharacterSet 和 NSMutableCharacterSet一致的类方法
//返回一个指定范围的字符集,取自小写字母字符集
+ (NSCharacterSet *)characterSetWithRange:(NSRange)aRange;
//返回一个包含当前字符串的字符集
+ (NSCharacterSet *)characterSetWithCharactersInString:(NSString *)aString;
//返回包含由给定位图表示形式确定的字符的字符集,此方法对于使用来自文件或其他外部数据源的数据创建字符集
+ (NSCharacterSet *)characterSetWithBitmapRepresentation:(NSData *)data;
//返回从位图表示中读取的字符集,存储在文件中给定的路径。
+ (nullable NSCharacterSet *)characterSetWithContentsOfFile:(NSString *)fName;
NSCharacterSet中的其它方法或属性：
//指定字符集是包含于在于当前字符集
- (BOOL)characterIsMember:(unichar)aCharacter;
//以二进制格式编码接收器的NSData对象,此格式适用于保存到文件或以其他方式传输或归档
@property (readonly, copy) NSData *bitmapRepresentation;
//反转字符集,仅包含当前字符集中不存在的字符
@property (readonly, copy) NSCharacterSet *invertedSet;
NSMutableCharacterSet中其它方法：
- (void)addCharactersInRange:(NSRange)aRange;
- (void)removeCharactersInRange:(NSRange)aRange;
- (void)addCharactersInString:(NSString *)aString;
- (void)removeCharactersInString:(NSString *)aString;
- (void)formUnionWithCharacterSet:(NSCharacterSet *)otherSet;
- (void)formIntersectionWithCharacterSet:(NSCharacterSet *)otherSet;
- (void)invert;
//*****************************************
延伸常与NSString 的一些方法结合使用, 来达到某些效果
//返回一个指定字符集分隔开的子字符串数组
- (NSArray*)componentsSeparatedByCharactersInSet:(NSCharacterSet *)separator NS_AVAILABLE(10_5, 2_0);
//返回一个去除两端指定字符集的字符串
- (NSString *)stringByTrimmingCharactersInSet:(NSCharacterSet *)set;
//返回指定字符集在当前字符串中的第一个符合条件的范围
- (NSRange)rangeOfCharacterFromSet:(NSCharacterSet *)searchSet;
NSArray的一些方法:
//在数组中子串之间插入指定字符
- (NSString *)componentsJoinedByString:(NSString *)separator;
应用
NSString *testString = @"This is the test string for %a*b*c&";
NSArray *divArr = [testString componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"abc"]];
NSLog(@"%@",divArr);
打印结果:
(
"This is the test string for %",
"*",
"*",
"&"
)
举例使用
1.去掉首尾空格
NSString *testString = @" This is the string contains whitespace in beginning and ending ";
NSString *whitesspaceStr = [testString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSLog(@"%@",whitesspaceStr);
打印结果: This is the string contains whitespace in beginning and ending
2.去除首尾指定字符串
NSString *str=@"哈哈呵呵嘿嘿吼吼";
NSCharacterSet *cs= [NSCharacterSet characterSetWithCharactersInString:@"哈吼"];
NSString *strResult = [str stringByTrimmingCharactersInSet:cs];
NSLog(@"%@",strResult);
打印结果: 呵呵嘿嘿
3.用指定字符串替代当前字符中的指定字符集中的字符串
NSMutableCharacterSet *letter = [NSMutableCharacterSet lowercaseLetterCharacterSet];
NSCharacterSet *decimalDigit = [NSCharacterSet decimalDigitCharacterSet];
[letter formUnionWithCharacterSet:decimalDigit];
NSString *string = @"g8!hgr3@09#23uiq%^78sjn453t78&13gesg*wt53(545y45)q3at";
NSLog(@"%@",[[string componentsSeparatedByCharactersInSet:letter] componentsJoinedByString:@"_"]);
[letter invert]; //字母数字反转
NSLog(@"%@",[[string componentsSeparatedByCharactersInSet:letter] componentsJoinedByString:@"_"]);
打印结果:
__!____@__#_____%^___________&______*____(______)____
g8_hgr3_09_23uiq__78sjn453t78_13gesg_wt53_545y45_q3at
4.去除所有空格
NSString *string = @" a b cd ef gh ij klm nopq rstu v w x y z ";
NSLog(@"%@",[[string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]] componentsJoinedByString:@""]);
打印结果: abcdefghijklmnopqrstuvwxyz
5.与NSPredicate结合使用压缩空格
NSString *string = @" Additional setup after loading the view.";
string = [string stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
NSArray *components = [string componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
components = [components filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"self <> ''"]];
string = [components componentsJoinedByString:@" "];
NSLog(@"%@", string);
打印结果: Additional setup after loading the view.
6.判断字符串是否只包含数字
- (BOOL)validateNumber:(NSString*)number {
BOOL res = YES;
NSCharacterSet* tmpSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789"];
int i = 0;
while (i < number.length) {
NSString * string = [number substringWithRange:NSMakeRange(i, 1)];
NSRange range = [string rangeOfCharacterFromSet:tmpSet];
if (range.length == 0) {
res = NO;
break;
}
i++;
}
return res;
}
7.在UITextFieldDelegate方法中, 限制只能输入数字和小数点, 且第一位不可以输入小数点, 小数点只能输入一个
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSCharacterSet *cs;
NSUInteger nDotLoc = [textField.text rangeOfString:@"."].location;
if (NSNotFound == nDotLoc && 0 != range.location) {
cs = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789."] invertedSet];
}else{
cs = [[NSCharacterSet characterSetWithCharactersInString:@"0123456789"] invertedSet];
}
NSString *filtered = [[string componentsSeparatedByCharactersInSet:cs] componentsJoinedByString:@""];
BOOL basicTest = [string isEqualToString:filtered];
if (!basicTest) {
return NO;
}
return YES;
}
