NSCharacterSet对字符串的处理

1、通过NSCharacterSet处理字符串

NSCharacterSet * set = [[NSCharacterSet characterSetWithCharactersInString:@"123"] invertedSet];
NSString * originalStr = @"1y3j g425";
NSString * finStr =  [[originalStr componentsSeparatedByCharactersInSet:set] componentsJoinedByString:@""];

其中 invertedSet 为倒置字符集

2、通过NSCharacterSet进行特殊字符转码

原始转码为：

NSString *outputStr = (NSString *) CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,(CFStringRef)input,NULL,(CFStringRef)@"!*'();:@&=+ $,/?%#[]",kCFStringEncodingUTF8));

NSCharacterSet转码：

NSString * originalStr2 = @"https://www.baidu.com";
NSString * characters = @"#[]@!$'()*+,;\"<>%{}|^~`/";
NSString * encodeStr = [originalStr2 stringByAddingPercentEncodingWithAllowedCharacters:[[NSCharacterSet characterSetWithCharactersInString:characters] invertedSet]];

或者通过系统提供的URLQueryAllowedCharacterSet等进行转码。

3、解码

encodeStr = [encodeStr stringByRemovingPercentEncoding];