NSString - 仅转换为纯字母（即删除重音符号+标点符号）

使用Objective-C语言，可以通过NSString的分类来实现将字符串中的非字母字符（包括重音符号和标点符号）删除的功能。下面是一个案例代码，演示了如何使用这个分类方法来转换字符串。

objc
#import 
@interface NSString (PureAlphabet)
- (NSString *)pureAlphabetString;
@end

objc
#import "NSString+PureAlphabet.h"
@implementation NSString (PureAlphabet)
- (NSString *)pureAlphabetString {
    NSMutableString *pureString = [NSMutableString stringWithString:self];
    NSCharacterSet *nonAlphabetCharacterSet = [[NSCharacterSet letterCharacterSet] invertedSet];
    [pureString replaceOccurrencesOfString:@" " withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"'" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"’" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"‘" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"–" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"-" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"." withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"," withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"!" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"?" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@";" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@":" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"\"" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"“" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"”" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"/" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"\\" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"(" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@")" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"[" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"]" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"{" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"}" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"<" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@">" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"|" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"@" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"#" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"$" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"^" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"&" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"*" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"_" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"=" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"+" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"~" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"`" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"…" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    [pureString replaceOccurrencesOfString:@"?" withString:@"" options:NSLiteralSearch range:NSMakeRange(0, [pureString length])];
    
    return [[pureString componentsSeparatedByCharactersInSet:nonAlphabetCharacterSet] componentsJoinedByString:@""];
}
@end

objc
#import 
#import "NSString+PureAlphabet.h"
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        NSString *originalString = @"Hello, 世界！This is a test string.";
        NSString *pureAlphabetString = [originalString pureAlphabetString];
        NSLog(@"%@", pureAlphabetString);
    }
    return 0;
}

HelloThisisateststring