截断一个字符串并在Objective-c的末尾添加省略号

Question

如何截断Objective-C中的字符串，然后在末尾添加省略号？

Answer 1

NSString *origString = @"A very long string blah blah blah";
const int clipLength = 18;
if([origString length]>clipLength)
{
    origString = [NSString stringWithFormat:@"%@...",[origString substringToIndex:clipLength]];
}

Answer 2

使用其中一种NSString方法截断，可能是最后一种：

– substringFromIndex:
– substringWithRange:
– substringToIndex:

然后使用NSString方法

– stringByAppendingString:

添加@"..."或任何您喜欢的ellopsis。

例如：

NSString *newString = [[string substringToIndex:12] stringByAppendingString:@"..."];

为了您的阅读乐趣，我推荐NSString Class Reference。

Answer 3

如果您希望截断并将省略号添加到最大为特定宽度的字符串，则此处是一个考虑字体和大小的实现：

+ (NSString *)stringByTruncatingString: (NSString *)string toWidth: (CGFloat)width withFont: (UIFont *)font
{
    #define ellipsis @"..."
    NSMutableString *truncatedString = [string mutableCopy];

    if ([string sizeWithAttributes: @{NSFontAttributeName: font}].width > width) {
        width -= [ellipsis sizeWithAttributes: @{NSFontAttributeName: font}].width;

        NSRange range = {truncatedString.length - 1, 1};

        while ([truncatedString sizeWithAttributes: @{NSFontAttributeName: font}].width > width) {
            [truncatedString deleteCharactersInRange:range];
            range.location--;
        }

        [truncatedString replaceCharactersInRange:range withString:ellipsis];
    }

    return truncatedString;
}

Answer 4

这样做不需要代码。 最简单的方法，

for drawRect

- (void)drawRect:(NSRect)dirtyRect{
    NSString *theText = @"bla blah bla bhla bla bla";
    NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
    [style setLineBreakMode:NSLineBreakByTruncatingTail];
    [theText drawInRect:dirtyRect withAttributes:[NSDictionary dictionaryWithObjectsAndKeys:style, NSParagraphStyleAttributeName,nil]];
}

听到我使用dirtyRect表示String的绘图区域，您可以根据需要更改它。

NSTextField的

NSTextField *_warningTF = [[NSTextField alloc]init];
[_warningTF setStringValue:@"sfdsf sdfdsfdsfdsfdsfdsfdsf  1234566789123456789sfdsf dsf dsfdsf"];
[_warningTF.cell setLineBreakMode:NSLineBreakByTruncatingTail];

Answer 5

我编写了一个简单的类别，用文字：

截断NSString

@interface NSString (TFDString)

- (NSString *)truncateByWordWithLimit:(NSInteger)limit;


@end


@implementation NSString (TFDString)

- (NSString *)truncateByWordWithLimit:(NSInteger)limit {
    NSRange r = NSMakeRange(0, self.length);
    while (r.length > limit) {
        NSRange r0 = [self rangeOfString:@" " options:NSBackwardsSearch range:r];
        if (!r0.length) break;
        r = NSMakeRange(0, r0.location);
    }
    if (r.length == self.length) return self;
    return [[self substringWithRange:r] stringByAppendingString:@"..."];
}


@end

<强>用法：

NSString *xx = @"This string is too long, somebody just need to take and truncate it, but by word, please.";
xx = [xx truncateByWordWithLimit:50];

结果：

This string is too long, somebody just need to...

希望它对某人有帮助。

Answer 6

drawWithRect：options：attributes：context方法有帮助。你可以试试这个：

[_ text drawWithRect：_textRect options： NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingTruncatesLastVisibleLine 属性：attributes context：nil];