例如,如果要键入。一种方法是键入“e”(0x65)+组合重音“”(0x301)。现在,如果你像这样键入“caf”并截断4个字符,你会得到“cafe”。这可能会在某些地方引起问题。

如果你不在乎这个,其他答案也行。否则,请执行以下操作:

// define the range you're interested in
NSRange stringRange = {0, MIN([myString length], 20)};

// adjust the range to include dependent chars
stringRange = [myString rangeOfComposedCharacterSequencesForRange:stringRange];

// Now you can create the short string
NSString *shortString = [myString substringWithRange:stringRange];

请注意,这样您的范围可能比初始范围长度长。在上面的caf示例中,您的范围将扩展到5的长度,即使您仍然有4个“glyphs”。如果你绝对需要一个长度小于你所说的,你需要检查这个。

NSString *myString = @"This is a string, it's a very long string, it's a very long string indeed";
myString = (myString.length > 20) ? [myString substringToIndex:20] : myString;

斯威夫特4

let trimToCharacter = 20
let shortString = String(myString.prefix(trimToCharacter))

较短的解决方案是:

NSString *shortString = ([myString length]>MINLENGTH ? [myString substringToIndex:MINLENGTH] : myString);

似乎有点微妙(如果字符串短于最大长度,则崩溃)

那为什么不把那部分修好呢?

NSRange stringRange = {0, MIN([myString length], 20)};

可以使用三元运算:

NSString *shortString = (stringRange.length <= [myString length]) ? myString : [myString substringWithRange:stringRange];

或者为了更好地控制最终结果:

if (stringRange.length > [myString length])
    // throw exception, ignore error, or set shortString to myString
else 
    shortString = [myString substringWithRange:stringRange];

最简单、最好的解决方案(文本末尾有3个点):

NSString *newText = [text length] > intTextLimit ? 
    [[text substringToIndex:intTextLimit] stringByAppendingString:@"..."] : 
        text;

 //Short the string if string more than 45 chars
    if([self.tableCellNames[indexPath.section] length] > 40) {

        // define the range you're interested in
        NSRange stringRange = {0, MIN([self.tableCellNames[indexPath.section] length], 40)};

        // adjust the range to include dependent chars
        stringRange = [self.tableCellNames[indexPath.section]
                       rangeOfComposedCharacterSequencesForRange:stringRange];

        // Now you can create the short string
        NSString *shortStringTitle = [self.tableCellNames[indexPath.section] substringWithRange:stringRange];

        shortStringTitle = [shortStringTitle stringByAppendingString:@"..."];

        titleLabel.text = shortStringTitle;

    } else {

        titleLabel.text = self.tableCellNames[indexPath.section];
    }

在不同位置(头部、尾部或中部)截断的延伸。

Swift 4.2及更新版本

extension String {
    enum TruncationPosition {
        case head
        case middle
        case tail
    }

   func truncated(limit: Int, position: TruncationPosition = .tail, leader: String = "...") -> String {
        guard self.count >= limit else { return self }

        switch position {
        case .head:
            return leader + self.suffix(limit)
        
        case .middle:
            let halfCount = (limit - leader.count).quotientAndRemainder(dividingBy: 2)
            let headCharactersCount = halfCount.quotient + halfCount.remainder
            let tailCharactersCount = halfCount.quotient
            return String(self.prefix(headCharactersCount)) + leader + String(self.suffix(tailCharactersCount))
        
        case .tail:
            return self.prefix(limit) + leader
        }
    }
}

如果要从最终用途截断:

[fileName substringToIndex:anyNumber];

[fileName substringFromIndex:anyNumber];