[英]Remove unallowed characters from NSString
I want to allow only specific characters for a string. 我想只允许字符串使用特定字符。
Here's what I've tried. 这是我尝试过的。
NSString *mdn = @"010-222-1111";
NSCharacterSet *allowedCharacterSet = [NSCharacterSet characterSetWithCharactersInString:@"+0123456789"];
NSString *trimmed = [mdn stringByTrimmingCharactersInSet:[allowedCharacterSet invertedSet]];
NSString *replaced = [mdn stringByReplacingOccurrencesOfString:@"-" withString:@""];
The result of above code is as below. 以上代码的结果如下。 The result of replaced is what I want.
替换的结果就是我想要的。
trimmed : 010-222-1111
replaced : 0102221111
What am I missing here? 我在这里想念什么? Why doesn't
invertedSet
work? 为什么
invertedSet
不起作用?
One more weird thing here. 这里还有一件奇怪的事情。 If I removed the
invertedSet
part like 如果我删除
invertedSet
部分
NSString *trimmed = [mdn stringByTrimmingCharactersInSet:allowedCharacterSet];
The result is 结果是
trimmed : -222-
I have no idea what makes this result. 我不知道是什么导致了这个结果。
stringByTrimmingCharactersInSet:
only removes occurrences in the beginning and the end of the string. stringByTrimmingCharactersInSet:
仅删除字符串开头和结尾的出现。 That´s why when you take inverted set, no feasible characters are found in the beginning and end of the string and thus aren't removed either. 这就是为什么当您采用倒置集时,在字符串的开头和结尾都找不到可行的字符,因此也不会删除它们的原因。
A solution would be: 一个解决方案是:
- (NSString *)stringByRemovingCharacters:(NSString*)str inSet:(NSCharacterSet *)characterSet {
return [[str componentsSeparatedByCharactersInSet:characterSet] componentsJoinedByString:@""];
}
stringByTrimmingCharactersInSet is only removing chars at the end and the beginning of the string, which results in -222-. stringByTrimmingCharactersInSet仅删除字符串末尾的字符,结果为-222-。 You have to do a little trick to remove all chars in the set
您必须做一些技巧来删除集合中的所有字符
NSString *newString = [[origString componentsSeparatedByCharactersInSet:
[[NSCharacterSet decimalDigitCharacterSet] invertedSet]]
componentsJoinedByString:@""];
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