Question

ObjC代码：

#pragma mark - bookNameFromString
+(NSString *) bookNameFromString:(NSString *)string{

NSMutableArray *newLineArray = [[NSMutableArray alloc]init];

NSUInteger length = [string length];
unichar buffer[length+1];
[string getCharacters:buffer range:NSMakeRange(0, length)];

NSInteger a = 0;
do {
    a = a+ 1;
    char current = buffer[a];
    if (current == '\n') {
        [newLineArray addObject:[NSNumber numberWithInteger:a]];
        break;
    }

} while (a <= length);

NSString *bookName  = nil;
if (newLineArray.count > 0 && newLineArray[0] != 0) {
    bookName = [string substringToIndex:[newLineArray[0]integerValue]];
}

return bookName;
}

在Swift中： 转换为swift

如何在objC中创建字符串缓冲区。

在向数组追加值时，会出现错误：无法转换类型＆＃39; String.CharacterView.Index＆＃39;预期参数类型＆＃39; Int＆＃39;

 // MARK: - bookNameFromString
func bookNameFromString(string:String) ->String {

let toFind:Character = "\n"
var newLineArray:[Int] = []
let lengthOfString = string.characters.count

var a = 0
repeat{
    a = a + 1
    if let index = string.characters.indexOf(toFind) {
        newLineArray.append(index) */ERROR: Cannot convert value of type 'String.CharacterView.Index' to expected argument type 'Int'/*
        break
    }
}while a < lengthOfString

print(newLineArray)

var bookName:String
if newLineArray.count > 0 && newLineArray[0] != 0{
    bookName = string.substringToIndex(string.startIndex.advancedBy(newLineArray[0]))
}

return bookName
}

Answer 1

这是尝试没有缓冲区并检查单个字符

func bookNameFromString(string : String) -> String?
{
  // separate string by linefeed character
  let array = string.componentsSeparatedByString("\n")
  // if string is empty or there is none or one linefeed - exit
  guard array.count > 1 else { return nil }
  // define a startindex which is 1 if the string starts with linefeed
  let startIndex = array[0].isEmpty ? 1 : 0
  // if there is no linefeed left - exit
  guard array.count > startIndex + 1 else { return nil }
  return  startIndex == 1 ?  "\n" + array[startIndex] : array[startIndex]
}


bookNameFromString("")                // -> nil
bookNameFromString("\n")              // -> nil
bookNameFromString("\n\n")            // -> \n
bookNameFromString("Hello")           // -> nil
bookNameFromString("\nHello")         // -> nil
bookNameFromString("Hello\n")         // -> Hello
bookNameFromString("Hello\nWorld")    // -> Hello
bookNameFromString("\nHello\n")       // -> \nHello
bookNameFromString("\nHello\nWorld")  // -> \nHello

如何创建字符串缓冲区来迭代它并转换类型＆＃39; String.CharacterView.Index＆＃39;期望参数类型＆＃39; Int＆＃39;？

1 个答案: