iphone - 规范化或规范化核心数据的字符串？

Question

我看过一些关于 Core Data 的 WWDC 视频，我正计划维护一个规范化的文本属性。假设我有以下数据:

originalString              normalizedString (+lowercase?)
Ønsker                      onsker
onsker                      onsker
Onsker                      onsker

当我查询我的模型时，我想按“normalizedString”对其进行排序，以便它忽略大小写和 Ø(或其他字符)。我还希望能够运行类似“以‘o’开头”的查询，并让它返回上面的 3 个词。

我试图避免做类似的事情:

[NSPredicate predicateWithFormat:@"(originalString like[cd] %@)"...

用于查询模型。我还尝试使用“originalString”进行排序。

我尝试了两种不同的方法但都没有成功，我的规范化字符串仍然保存为原始字符串(我覆盖了我创建的类别中的 setter ):

1. 调用 decomposedStringWithCanonicalMapping:

   // ...
   [normalizedString decomposedStringWithCanonicalMapping];
   // ...
   

2. 已关注 this example :

   // ...
   CFStringNormalize((CFMutableStringRef)normalizedString, kCFStringNormalizationFormD);
   CFStringFold((CFMutableStringRef)normalizedString, kCFCompareCaseInsensitive | kCFCompareDiacriticInsensitive | kCFCompareWidthInsensitive, NULL);
   

关于如何实现我的目标有什么想法吗？

编辑:这是我重写的 setter，我知道它被称为:

- (void) setNormalizedName:(NSString *)newNormalizedName
{
    NSMutableString *normalizedString;
    if (![self.lastName length] == 0) {
        normalizedString = [NSMutableString stringWithString:self.lastName];
    } else {
        normalizedString = [NSMutableString stringWithString:self.firstName];
    }

//    CFStringNormalize((CFMutableStringRef)normalizedString, kCFStringNormalizationFormD);
//    CFStringFold((CFMutableStringRef)normalizedString, kCFCompareCaseInsensitive | kCFCompareDiacriticInsensitive | kCFCompareWidthInsensitive, NULL);
    [normalizedString decomposedStringWithCanonicalMapping];

    [self willChangeValueForKey:@"normalizedName"];
    [self setPrimitiveValue:normalizedString forKey:@"normalizedName"];
    [self didChangeValueForKey:@"normalizedName"];
}

Answer 1

您应该覆盖“主要”属性(例如 firstName、lastName)的 setter，而不是“派生”属性的 setter。

还要注意 decomposedStringWithCanonicalMapping 返回一个新字符串，它不会修改接收器。

代码大致如下所示(未经编译器检查):

- (void) setFirstName:(NSString *)firstName
{
    [self willChangeValueForKey:@"firstName"];
    [self setPrimitiveValue:firstName forKey:@"firstName"];
    [self didChangeValueForKey:@"firstName"];
    [self updateNormalizedName];
}

- (void) setLastName:(NSString *)lastName
{
    [self willChangeValueForKey:@"lastName"];
    [self setPrimitiveValue:lastName forKey:@"lastName"];
    [self didChangeValueForKey:@"lastName"];
    [self updateNormalizedName];
}

- (void) updateNormalizedName
{
    NSString *normalizedString;
    if ([self.lastName length] > 0) {
        normalizedString = [self.lastName decomposedStringWithCanonicalMapping];
    } else {
        normalizedString = [self.firstName decomposedStringWithCanonicalMapping];
    }
    self.normalizedString = normalizedString;
}