如何在NSMutableString中修剪""和"\n"

- (void)trimString:(NSMutableString *)string {
    NSCharacterSet *whitespaceCharacterSet = [NSCharacterSet whitespaceCharacterSet];
    NSRange range = NSMakeRange(0, string.length);
    [string replaceOccurrencesOfCharactersInSet:whitespaceCharacterSet withString:@"" options:0 range:range];
}

NSMutableString *string = [NSMutableString stringWithString:@"Hello, world!\n"];
[self trimString:string];
NSLog(@"%@", string); // 输出 "Hello, world!"

NSCharacterSet *whitespaceCharacterSet = [NSCharacterSet whitespaceCharacterSet];
NSCharacterSet *newlineCharacterSet = [NSCharacterSet newlineCharacterSet];
NSCharacterSet *trimCharacterSet = [whitespaceCharacterSet mutableCopy];
[trimCharacterSet formUnionWithCharacterSet:newlineCharacterSet];