SWIFT用NSInputStream实现文件按行读取

背景

最近写个App，里面读取大文件，用NSData方式能把文件内容全部读取，但因为文件大，害怕占用内存也大，就想用缓冲方式，一行一行读取。结果找了很多地方，没这样的代码，从XCode里的帮助也找不到线索，很是头疼。这里翻译的文章也没有真正到位地解决问题，希望有经验的朋友进行指导，对编程细节和思路进拓展。

提问

I'm trying to match reading files in my iPhone app just like in Android with InputStream.

How I do it in Android is like this:

我正在尝试匹配我的iPhone应用程序中的读文件，就像Android中的InputStream一样。我在Android中实现代码如下：

String line = "";
int count = 0;
FileInputStream fis = tempContext.openFileInput("myfile.txt"); // This just get File Path
BufferedReader br = new BufferedReader(new InputStreamReader(fis));
// LOAD ARRAY LINE BY LINE
try {
while (count<myMaxNumber) {
line = br.readLine();
myArray[count] = line;
count++;
}
fis.close();
br.close();
} catch (IOException e) {
e.printStackTrace();
}

I've used code to write to a txt file successfully, but I cannot read line by line. It will read the entire file as it's made to do, and add the '\n' breaks, but I want it to read one line, and go to the next line until there are no bytes我已经使用代码成功写入txt文件，但我无法逐行读取。它将按原样读取整个文件，并添加'\ n'分隔，但我希望它读取一行，然后转到下一行直到没有字节。

if (checkFileExists()) {
            
            let dir = dirs![0]; //documents directory
            var getDocPath = dir.stringByAppendingPathComponent("favlist.txt")
            
            var data : NSData = NSData(contentsOfFile: getDocPath)!
            var inputStream : NSInputStream = NSInputStream(data: data)
            
            let bufferSize = 1500
            var myBuffer = Array<UInt8>(count: bufferSize, repeatedValue: 0)
            
            inputStream.open()
            
            var bytesRead = inputStream.read(&myBuffer, maxLength: bufferSize)
            var tempStuff = NSString(bytes: &myBuffer, length: bytesRead, encoding: NSUTF8StringEncoding)
            
            if (inputStream.hasBytesAvailable) {
                for (var a = 0; a < myFavListMax; a++) {
                    // I KNOW THIS SETS THE ENTIRE TEXT FILE WITH NEW LINE BREAKS IN EVERY INDEX
                   //  I NEED SOMETHING WHICH READS LINE BY LINE
                    myFavList[a] = String(tempStuff!)
                }
            }
            
            inputStream.close()
}

Is there another way to do this? What is the equivalent to the android way for SWIFT in IOS 8? Can I read by Array and add '\n' as an indication to add append when using an array to read?还有另一种方法吗？在IOS 8中，SWIFT处理方式有和android方式一样的吗？
我可以通过Array读取并在使用数组读取时添加'\ n'作为指示指导添加追加吗？

回答1

I didn't have much time to get back to this but I guess this doesn't exist in NSInputStream so I just loaded everything in a NSString, then copy to a String and load into a new Array by splitting.

Works fine for what I expected!

我没有太多时间回到这个，但我想这在NSInputStream中不存在，所以我只是将所有内容加载到NSString中，然后复制到String并通过拆分加载到新的Array中。

适合我的预期！

if (checkFileExists()) {
            
            let dir = dirs![0]; //documents directory
            var getDocPath = dir.stringByAppendingPathComponent("favlist.txt")
            
            var data : NSData = NSData(contentsOfFile: getDocPath)!
            var inputStream : NSInputStream = NSInputStream(data: data)
            
            let bufferSize = 1500
            var myBuffer = Array<UInt8>(count: bufferSize, repeatedValue: 0)
            
            inputStream.open()
            
            var bytesRead = inputStream.read(&myBuffer, maxLength: bufferSize)
            var textFileContents = NSString(bytes: &myBuffer, length: bytesRead, encoding: NSUTF8StringEncoding)
            var a : String = textFileContents!
            var textFileContentsTempArray = split(a){$0 == "\n"}
            
            for (var a = 0; a < myFavListMax; a++) {
                    myFavList[a] = textFileContentsTempArray[a]
                }
            
            inputStream.close()
}

友情链接