Added variable for the duration of the animation
Added variable for the duration of the animation

hanhailong/practice-swift,hanhailong/practice-swift,hanhailong/practice-swift,nguyenantinhbk77/practice-swift,nguyenantinhbk77/practice-swift,domenicosolazzo/practice-swift,domenicosolazzo/practice-swift,domenicosolazzo/practice-swift,hanhailong/practice-swift,nguyenantinhbk77/practice-swift,domenicosolazzo/practice-swift,nguyenantinhbk77/practice-swift