objective-c - 如何从 NSString 的右端删除空格？

Question

这会删除字符串两端的空格:

NSString *newString = [oldString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];

如何删除字符串右端的空格？

更新:accepted answer 中的代码现在是 SSToolkit 的一部分.耶!

Answer 1

更新:快速基准测试显示 Matt's own adaption , 基于 Max' & 我的，表现最好。

@implementation NSString (TrimmingAdditions)

- (NSString *)stringByTrimmingLeadingCharactersInSet:(NSCharacterSet *)characterSet {
    NSUInteger location = 0;
    NSUInteger length = [self length];
    unichar charBuffer[length];    
    [self getCharacters:charBuffer];

    for (location; location < length; location++) {
        if (![characterSet characterIsMember:charBuffer[location]]) {
            break;
        }
    }

    return [self substringWithRange:NSMakeRange(location, length - location)];
}

- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
    NSUInteger location = 0;
    NSUInteger length = [self length];
    unichar charBuffer[length];    
    [self getCharacters:charBuffer];

    for (length; length > 0; length--) {
        if (![characterSet characterIsMember:charBuffer[length - 1]]) {
            break;
        }
    }

    return [self substringWithRange:NSMakeRange(location, length - location)];
}

@end

然后:

NSString *trimmedString = [yourString stringByTrimmingTrailingCharactersInSet:[NSCharacterset whitespaceAndNewlineCharacterSet]];

或前导空格:

NSString *trimmedString = [yourString stringByTrimmingLeadingCharactersInSet:[NSCharacterset whitespaceAndNewlineCharacterSet]];

它以抽象方式实现，因此您可以将它与任何可能的 NSCharacterSet 一起使用，whitespaceAndNewlineCharacterSet 只是其中之一。

为了方便起见，您可能希望添加这些包装器方法:

- (NSString *)stringByTrimmingLeadingWhitespace {
    return [self stringByTrimmingLeadingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
}

- (NSString *)stringByTrimmingTrailingWhitespace {
    return [self stringByTrimmingTrailingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
}

- (NSString *)stringByTrimmingLeadingWhitespaceAndNewline {
    return [self stringByTrimmingLeadingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}

- (NSString *)stringByTrimmingTrailingWhitespaceAndNewline {
    return [self stringByTrimmingTrailingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
}

编辑:使用 charBuffer 恢复到初始版本以获得更好的性能。