objective-c - 有没有办法计算 NSString 的行数？

Question

Possible Duplicate:
How to count the number of lines in an Objective-C string (NSString)?

有没有办法计算 NSString 的行数？

NSString * myString = @"line 1 \n line 2 \n";

行数 = 3;

谢谢

Answer 1

注意 componentsSeparatedByString 不够智能，无法检测 mac/windows/unix 行结尾之间的情况。在 \n 上分隔适用于 windows/unix 行结尾，但不适用于经典的 mac 文件(并且有一些流行的 mac 编辑器默认情况下仍然使用这些行结尾)。您确实应该检查 \r\n 和 \r。

此外，componentsSeparatedByString: 速度慢且占用内存。如果您关心性能，您应该重复搜索换行符并计算结果数量:

NSString * myString = @"line 1 \n line 2 \n";

int lineCount = 1;
NSUInteger characterLocation = 0;
NSCharacterSet *newlineCharacterSet = [NSCharacterSet newlineCharacterSet];
while (characterLocation < myString.length) {
  characterLocation = [myString rangeOfCharacterFromSet:newlineCharacterSet options:NSLiteralSearch range:NSMakeRange(characterLocation, (myString.length - characterLocation))].location;

  if (characterLocation == NSNotFound) {
    break;
  }

  // if we are at a \r character and the next character is a \n, skip the next character
  if (myString.length >= characterLocation &&
      [myString characterAtIndex:characterLocation] == '\r' &&
      [myString characterAtIndex:characterLocation + 1] == '\n') {
    characterLocation++;
  }

  lineCount++;
  characterLocation++;
}

NSLog(@"%i", lineCount);