问题:

I am trying to NSLog the number of megs my NSData object is however currently all I can get is bytes by using

NSLog(@"%u", myData.length);

So how would I change this NSLog statement so I can see something like

2.00 megs

any help would be appreciated.

回答1:

There are 1024 bytes in a kilobyte and 1024 kilobytes in a megabyte, so...

NSLog(@"File size is : %.2f MB",(float)myData.length/1024.0f/1024.0f);

Mind you, this is a simplistic approach that couldn't really properly accommodate for byte sizes below 1,048,576 bytes or above 1,073,741,823 bytes. For a more complete solution that can handle varying file sizes, see: ObjC/Cocoa class for converting size to human-readable string?

Or for OS X 10.8+ and iOS 6+

NSLog(@"%@", [[NSByteCountFormatter new] stringFromByteCount:data.length]);

In Swift:

print(ByteCountFormatter().string(fromByteCount: Int64(data.count)))

回答2:

For Swift 3, in Mb:

let countBytes = ByteCountFormatter()
countBytes.allowedUnits = [.useMB]
countBytes.countStyle = .file
let fileSize = countBytes.string(fromByteCount: Int64(dataToMeasure!.count))

print("File size: \(fileSize)")