如何在NSString中正确编码Unicode字符？ [英] How do I properly encode Unicode characters in my NSString?

问题描述

我创建了许多字符串，将它们连接成CSV格式，然后将字符串作为附件发送电子邮件。

I create a number of strings, concatenate them together into CSV format, and then email the string as an attachment.

当这些字符串仅包含ASCII字符时，将生成CSV文件并通过电子邮件发送。当我包含非ASCII字符时，结果字符串变得格式错误，并且未正确创建CSV文件。 （电子邮件视图显示附件，但不会发送。）

When these strings contain only ASCII characters, the CSV file is built and emailed properly. When I include non-ASCII characters, the result string becomes malformed and the CSV file is not created properly. (The email view shows an attachment, but it is not sent.)

例如，这有效：

uncle bill's house of pancakes

但这不是（请注意卷曲撇号）：

But this doesn't (note the curly apostrophe):

uncle bill’s house of pancakes

问题

如何正确创建和编码最终字符串，以便包含所有有效的unicode字符和结果字符串是否正确形成？

Question

How do I create and encode the final string properly so that all valid unicode characters are included and the result string is formed properly?

• 字符串是通过UITextField创建，然后写入并从核心数据存储读取。

• The strings are created via a UITextField and then are written to and then read from a Core Data store.

这表明问题在于初始创建和编码字符串： NSString unicode编码问题

This suggests that the problem lies in the initial creation and encoding of the string: NSString unicode encoding problem

我不想这样做： 从objective-c中的NSString中删除非ASCII字符

I don't want to have to do this: remove non ASCII characters from NSString in objective-c

编写字符串并从数据存储中读取数据。字符串在应用程序的表视图中正确显示（单独）。只有在为电子邮件附件连接字符串时才会出现此问题。

The strings are written and read to/from the data store fine. The strings display properly (individually) in the app's table views. The problem only manifests when concatenating the strings together for the email attachment.

我将我的字符串连接在一起如下：

I concatenate my strings together like this:

[reportString appendFormat:@"%@,", category];
[reportString appendFormat:@"%@,", client];
[reportString appendFormat:@"%@\n", detail];
etc.

用无聊的引号替换卷曲引号使其有效，但我不知道想要这样做：

Replacing curly quotes with boring quotes makes it work, but I don't want to do it this way:

- (NSMutableString *)cleanString:(NSString *)activity {
    NSString *temp1 = [activity stringByReplacingOccurrencesOfString:@"’" withString:@"'"];
    NSString *temp2 = [temp1 stringByReplacingOccurrencesOfString:@"‘" withString:@"'"];
    NSString *temp3 = [temp2 stringByReplacingOccurrencesOfString:@""" withString:@"\""];
    NSString *temp4 = [temp3 stringByReplacingOccurrencesOfString:@""" withString:@"\""];
    return [NSMutableString temp4];
}

修改：
电子邮件是已发送：

The email is sent:

    NSString *attachment = [self formatReportCSV];
    [picker addAttachmentData:[attachment dataUsingEncoding:NSStringEncodingConversionAllowLossy] mimeType:nil fileName:@"MyCSVFile.csv"];

其中 formatReportCSV 是连接和返回csv字符串。

where formatReportCSV is the function that concatenates and returns the csv string.

推荐答案

您似乎遇到了字符串编码问题。如果没有看到你的核心数据模型是什么样的，我认为这个问题归结为下面代码重现的问题。

You seem to be running across a string encoding issue. Without seeing what your Core Data model looks like, I'd assume the issue boils down to the issue reproduced by the code below.

NSString *string1 = @"Uncle bill’s house of pancakes.";
NSString *string2 = @" Appended with some garbage's stuff.";
NSMutableString *mutableString = [NSMutableString stringWithString: string1];
[mutableString appendString: string2];
NSLog(@"We got: %@", mutableString);
// We got: Uncle bill’s house of pancakes. Appended with some garbage's stuff.

NSData *storedVersion = [mutableString dataUsingEncoding: NSStringEncodingConversionAllowLossy];
NSString *restoredString = [[NSString alloc] initWithData: storedVersion encoding: NSStringEncodingConversionAllowLossy];
NSLog(@"Restored string with NSStringEncodingConversionAllowLossy: %@", restoredString);
// Restored string with NSStringEncodingConversionAllowLossy: 

storedVersion = [mutableString dataUsingEncoding: NSUTF8StringEncoding];
restoredString = [[NSString alloc] initWithData: storedVersion encoding: NSUTF8StringEncoding];
NSLog(@"Restored string with UTF8: %@", restoredString);
// Restored string with UTF8: Uncle bill’s house of pancakes. Appended with some garbage's stuff.

注意第一个字符串（使用ASCII编码）无法处理非ASCII的存在character（如果你使用 dataUsingEncoding：allowsLossyConversion：，第二个参数是 YES ）。

Note how the first string (encoded using ASCII) couldn't handle the presence of the non-ASCII character (it can if you use dataUsingEncoding:allowsLossyConversion: with the second parameter being YES).

此代码应解决问题：

NSString *attachment = [self formatReportCSV];
[picker addAttachmentData:[attachment dataUsingEncoding: NSUTF8StringEncoding] mimeType:nil fileName:@"MyCSVFile.csv"];

注意：如果你需要处理非UTF8，你可能需要使用UTF16字符串编码之一像日语这样的语言。

Note: you may need to use one of the UTF16 string encodings if you need to handle non-UTF8 languages like Japanese.

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