How to post and delete a Tweet

To post a Tweet or how to configure twitter in ios 11:

Tap the Tweet icon
Compose your message and tap Tweet.
To save a draft: Tap the X in the Tweet compose window and select Save draft. Access it (and other drafts) later by tapping the Tweet icon, then the draft icon

To reply to or mention an account:

Tap the @ symbol to bring up a list of suggested accounts you follow.
As you start typing a username the list will narrow down to fewer results.
Once you've found the account you're looking for, tap their username and it will populate in the Tweet. Your character count will adjust, as needed.
Learn about the difference between replies and mentions.

To include a hashtag in your Tweet:

Tap the # symbol and a list of current trends will appear.
You can choose to include one of these suggested hashtags (tap to select) or add your own hashtag text.

To post a photo or GIF with your Tweet:

Tap the photo icon to take a photo, or to choose a photo or GIF from your gallery. You can select up to four photos in a Tweet.
When you are finished selecting your photos, tap Add.
Once you have taken or selected your photo, you will have the option to apply a filter and crop the image by tapping the pencil icon on the attached photo(s).
You can tag people in your photo(s) by tapping Who’s in this photo? Type in the full name or @ username and then tap Done.
Learn more information about Tweeting photos, including instructions for changing your photo tagging privacy settings.