NSInputStream read:maxLength: cannot read data, returns -1

Question

In Objective C, I have somethng like this:

uint8_t f[400000];
NSString *Str;
unsigned int count = 0;
NSError* error = nil;
Str = [[NSString alloc]initWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"Test" ofType:@"txt"] encoding:NSUTF8StringEncoding error:&error];
@try {
    NSInputStream *fin = [NSInputStream inputStreamWithData:[Str dataUsingEncoding:NSUTF8StringEncoding]];
    count = [fin read:f maxLength:400000];

}
@catch (NSException * e) {
    NSLog(@"Exception: %@", e);
}
@finally {
    NSLog(@"finally");
}

I am converting nsstring to nsinputstream and then trying to read the content

But after I debug the code, count has -1 in it, ie an error occurred while reading. I don't understand what am I doing wrong here! Can someone please help me out.

: Test.txt is a plain text file with content as just "Hello" and debugging shows Str is initialised with the content. ： Test.txt是纯文本文件，内容仅为“ Hello”，并且调试显示Str已使用内容初始化。 That means something is wrong in the try block.

Any help is appreciated.

Answer 1

You didn't open the stream. You cannot read from/write to a NSStream ( NSInputStream and NSOutputStream are both subclasses of NSStream ) without opening it first. Just call open on your stream object prior to reading from it.