• 获取设备总的存储空间：

// iOS11 之前使用该方法获取
- (long)getTotalDiskSpace{
    long totalsize = -1;
    NSError *error = nil;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];
    if (dictionary)
    {
       NSNumber *_total = [dictionary objectForKey:NSFileSystemSize];
       totalsize = [_total unsignedLongLongValue];
    } else
    {
       NSLog(@"Error Obtaining System Memory Info: Domain = %@, Code = %ld", [error domain], (long)[error code]);
    }
    return totalsize;
}

// iOS11 之后使用该方法获取
- (void)getTotalDiskSpace{
    NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:NSTemporaryDirectory()];
    NSDictionary *results = [fileURL resourceValuesForKeys:@[NSURLVolumeAvailableCapacityForImportantUsageKey] error:nil];
    NSLog(@"剩余可用空间:%@",results[NSURLVolumeAvailableCapacityForImportantUsageKey]);
}

• 获取设备可用存储空间：

//iOS11 之前使用该方法获取
-(long)getFreeDiskSpace{
    long freesize = -1;
    NSError *error = nil;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];
    if (dictionary)
    {
       NSNumber *_free = [dictionary objectForKey:NSFileSystemFreeSize];
       freesize = [_free unsignedLongLongValue];
    } else
    {
       NSLog(@"Error Obtaining System Memory Info: Domain = %@, Code = %ld", [error domain], (long)[error code]);
    }
    return  freesize;
}

// iOS11 之后使用该方法获取
- (void)getTotalDiskSpace{
    NSURL *fileURL = [[NSURL alloc] initFileURLWithPath:NSTemporaryDirectory()];
    NSDictionary *results = [fileURL resourceValuesForKeys:@[NSURLVolumeTotalCapacityKey] error:nil];
    NSLog(@"剩余可用空间:%@",results[NSURLVolumeTotalCapacityKey]);
}