不兼容的整数到指针转换？什么？ [英] Incompatible integer to pointer conversion? what?

问题描述

我正在读取一个用UTF8编码的txt文件。

I am reading a txt file that was encoded with UTF8.

我正在读取该文件。我有这样的行：

I am now reading the file. I have this lines:

- (NSString *) readFromFile {

    NSArray *paths = NSSearchPathForDirectoriesInDomains
    (NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];


    NSString *fileName = [NSString stringWithFormat:@"%@/textfile.txt",
                          documentsDirectory];
    return [[NSString alloc] initWithContentsOfFile:fileName
                        usedEncoding:NSUTF8StringEncoding
                        error:nil];
}

我在最后一行有这个错误：

I have this error on the last line:

与指针转换不兼容的整数将int发送到NSUTF8StringEncoding类型的参数*

为什么？

推荐答案

这里的关键是使用 d 编码中的d。

The key here is the "d" in "usedEncoding".

该参数用于将信息传递回调用者关于使用的编码以读取文件。

That parameter serves to pass information back to the caller about the encoding used to read the file.

这意味着它是 NSString 类，它通知调用者它用于创建对象的编码。文件中的原始数据 - 不可以指示班级使用哪种编码的调用者。

This means that it is the NSString class that informs the caller which encoding it used to create the object from the raw data in the file - and not the caller that can instruct the class about which encoding to employ.

要获取此信息，您需要声明变量并传递对它的引用，以便 NSString 类对象可以将信息放入其中，以便稍后在需要时阅读。

To get this information, you need to declare a variable and pass a reference to it so the NSString class object can put the information into it for you to read later if you need the information.

NSStringEncoding enc;

NSString *result = [[NSString alloc] initWithContentsOfFile:fileName
                    usedEncoding: &enc
                    error:nil];

// Do something with the information about the encoding used
if ( enc == NSUTF8StringEncoding ) {
     // ...
}

return result;

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