从这里的答案来看:https://stackoverflow.com/a/5691567/251012

- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
    NSRange rangeOfLastWantedCharacter = [self rangeOfCharacterFromSet:[characterSet invertedSet]
                                                               options:NSBackwardsSearch];
    if (rangeOfLastWantedCharacter.location == NSNotFound) {
        return @"";
    }
    return [self substringToIndex:rangeOfLastWantedCharacter.location+1]; // non-inclusive
}

解决方案在这里描述:如何从NSString的右端删除空白?

添加以下类别到NSString:

- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
    NSRange rangeOfLastWantedCharacter = [self rangeOfCharacterFromSet:[characterSet invertedSet]
                                                               options:NSBackwardsSearch];
    if (rangeOfLastWantedCharacter.location == NSNotFound) {
        return @"";
    }
    return [self substringToIndex:rangeOfLastWantedCharacter.location+1]; // non-inclusive
}

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

你可以这样使用它:

[yourNSString stringByTrimmingTrailingWhitespaceAndNewlineCharacters]

在Swift中删除字符串开头和结尾的空格:

斯威夫特3

string.trimmingCharacters(in: .whitespacesAndNewlines)

Swift以前的版本

string.stringByTrimmingCharactersInSet(.whitespaceAndNewlineCharacterSet()))

从这里的答案来看:https://stackoverflow.com/a/5691567/251012

- (NSString *)stringByTrimmingTrailingCharactersInSet:(NSCharacterSet *)characterSet {
    NSRange rangeOfLastWantedCharacter = [self rangeOfCharacterFromSet:[characterSet invertedSet]
                                                               options:NSBackwardsSearch];
    if (rangeOfLastWantedCharacter.location == NSNotFound) {
        return @"";
    }
    return [self substringToIndex:rangeOfLastWantedCharacter.location+1]; // non-inclusive
}

给你…

- (NSString *)removeEndSpaceFrom:(NSString *)strtoremove{
    NSUInteger location = 0;
    unichar charBuffer[[strtoremove length]];
    [strtoremove getCharacters:charBuffer];
    int i = 0;
    for(i = [strtoremove length]; i >0; i--) {
        NSCharacterSet* charSet = [NSCharacterSet whitespaceCharacterSet];
        if(![charSet characterIsMember:charBuffer[i - 1]]) {
            break;
        }
    }
    return [strtoremove substringWithRange:NSMakeRange(location, i  - location)];
}

现在就叫它。假设你有一个字符串，它前面有空格，后面也有空格，你只想去掉末尾的空格，你可以这样调用它:

NSString *oneTwoThree = @"  TestString   ";
NSString *resultString;
resultString = [self removeEndSpaceFrom:oneTwoThree];

resultString的结尾将没有空格。

我想出了这个函数，它的行为基本类似于Alex的答案:

-(NSString*)trimLastSpace:(NSString*)str{
    int i = str.length - 1;
    for (; i >= 0 && [str characterAtIndex:i] == ' '; i--);
    return [str substringToIndex:i + 1];
}

whitespaceCharacterSet除了空格本身还包括制表符，在我的情况下不能出现。所以我想一个简单的比较就足够了。