if (label.lineBreakMode != NSLineBreakByCharWrapping) {
       return nil;
   }

   NSMutableArray *linesArr = [[NSMutableArray alloc] init];
   NSCharacterSet *wordSeparators = [NSCharacterSet whitespaceAndNewlineCharacterSet];

   NSString *currentLineText = label.text;
   int textLength = label.text.length;

   NSRange rCurrentLineRange = NSMakeRange(0, textLength);
   NSRange rWhiteSpace = NSMakeRange(0, 0);
   NSRange rRemainingText = NSMakeRange(0, textLength);

   BOOL done = NO;
   while (!done) {
       rWhiteSpace.location = rWhiteSpace.location + rWhiteSpace.length;
       rWhiteSpace.length = textLength - rWhiteSpace.location;
       rWhiteSpace = [label.text rangeOfCharacterFromSet:wordSeparators options:NSCaseInsensitiveSearch range:rWhiteSpace];
       if (rWhiteSpace.location == NSNotFound) {
           rWhiteSpace.location = textLength;
           done = YES;
       }

       NSRange rTextRange = NSMakeRange(rRemainingText.location, rWhiteSpace.location - rRemainingText.location);
       NSString *textSubString = [label.text substringWithRange:rTextRange];
       CGSize sizeText = [textSubString sizeWithFont:label.font forWidth:200 lineBreakMode:NSLineBreakByCharWrapping];
       if (sizeText.width > label.bounds.size.width) {
           [linesArr addObject:[currentLineText stringByTrimmingCharactersInSet:wordSeparators]];
           rRemainingText.location = rCurrentLineRange.location + rCurrentLineRange.length;
           rRemainingText.length = textLength - rRemainingText.location;
           continue;
       }

       rCurrentLineRange = rTextRange;
       currentLineText = textSubString;
   }
   [linesArr addObject:[currentLineText stringByTrimmingCharactersInSet:wordSeparators]];

   return linesArr;
}

这里有个更好的方法，支持中英文都没问题，使用的是CoreText处理，需要引入CoreText框架，并且 #import

+ (NSArray *)getSeparatedLinesFromLabel:(UILabel *)label
{
   NSString *text = [label text];
   UIFont   *font = [label font];
   CGRect    rect = [label frame];
   
   CTFontRef myFont = CTFontCreateWithName((__bridge CFStringRef)([font fontName]), [font pointSize], NULL);
   NSMutableAttributedString *attStr = [[NSMutableAttributedString alloc] initWithString:text];
   [attStr addAttribute:(NSString *)kCTFontAttributeName value:(__bridge id)myFont range:NSMakeRange(0, attStr.length)];
   
   CTFramesetterRef frameSetter = CTFramesetterCreateWithAttributedString((__bridge CFAttributedStringRef)attStr);
   
   CGMutablePathRef path = CGPathCreateMutable();
   CGPathAddRect(path, NULL, CGRectMake(0,0,rect.size.width,100000));
   
   CTFrameRef frame = CTFramesetterCreateFrame(frameSetter, CFRangeMake(0, 0), path, NULL);
   
   NSArray *lines = (__bridge NSArray *)CTFrameGetLines(frame);
   NSMutableArray *linesArray = [[NSMutableArray alloc]init];
   
   for (id line in lines)
   {
       CTLineRef lineRef = (__bridge CTLineRef )line;
       CFRange lineRange = CTLineGetStringRange(lineRef);
       NSRange range = NSMakeRange(lineRange.location, lineRange.length);
       
       NSString *lineString = [text substringWithRange:range];
       [linesArray addObject:lineString];
   }
   return (NSArray *)linesArray;
}