NSInputStream read：maxLength：无法读取数据，返回-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. 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.