I'm trying to find a file size. But my length

问题:

I'm trying to find a file size.

 NSFileHandle *output = [NSFileHandle fileHandleForWritingAtPath:self.finalPath]; 
//seek to begin of the file
[output seekToFileOffset:0];
NSData *mydata = [output availableData];
NSLog(@"length: %d", [mydata length]);

But my length is equl to zero. Why?

回答1:

availableData is for reading files. If you just want to find out the size of a file, you don't actually have to open it. Just use NSFileManager like this:

NSDictionary *attributes = [[NSFileManager defaultManager] attributesOfItemAtPath:self.finalPath error:NULL];
unsigned long long fileSize = [attributes fileSize]; // in bytes

回答2:

[fileHandler seekToEndOfFile], this returns the length of your file data, your code [output seekToFileOffset:0] means from 0-0,so there is no data