How to detect total available/free disk space on the iPhone/iPad device on iOS 11

Question

In iOS 11, I am not able to get the correct free size of the device(disk space) from the Dictionary key NSFileSystemFreeSize. Instead giving 34.4 GB it gives 4 GB free space.

Below is the code I am using

pragma mark - Formatter

- (NSString *)memoryFormatter:(long long)diskSpace
{
    NSString *formatted;
    double bytes = 1.0 * diskSpace;
    double megabytes = bytes / MB;
    double gigabytes = bytes / GB;
    if (gigabytes >= 1.0)
        formatted = [NSString stringWithFormat:@"%.2f GB", gigabytes];
    else if (megabytes >= 1.0)
        formatted = [NSString stringWithFormat:@"%.2f MB", megabytes];
    else
        formatted = [NSString stringWithFormat:@"%.2f bytes", bytes];
    
    return formatted;
}

#pragma mark - Methods

- (NSString *)totalDiskSpace {
    long long space = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemSize] longLongValue];
    return [self memoryFormatter:space];
}

- (NSString *)freeDiskSpace {
    long long freeSpace = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemFreeSize] longLongValue];
    return [self memoryFormatter:freeSpace];
}

- (NSString *)usedDiskSpace {
    return [self memoryFormatter:[self usedDiskSpaceInBytes]];
}

- (CGFloat)totalDiskSpaceInBytes {
    long long space = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemSize] longLongValue];
    return space;
}

- (CGFloat)freeDiskSpaceInBytes {
    long long freeSpace = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemFreeSize] longLongValue];
    return freeSpace;
}

- (CGFloat)usedDiskSpaceInBytes {
    long long usedSpace = [self totalDiskSpaceInBytes] - [self freeDiskSpaceInBytes];
    return usedSpace;
}

Answer 1

So if people have the problem of not getting the correct free size, use NSURL resourceValuesForKeys to get the free space.

[ fileURL resourceValuesForKeys:@[NSURLVolumeAvailableCapacityForImportantUsageKey ] error:&error];
        
double = availableSizeInBytes = [ results[NSURLVolumeAvailableCapacityForImportantUsageKey] doubleValue ];

Reference Why is `volumeAvailableCapacityForImportantUsage` zero?