Here are a couple of suggestions from my end -
This is the most preferred keyboard for iOS. As stated in the previous response, it is one of the highly opted keyboard by iPhone users. The word prediction, tracing and normal typing - all of them tend to be smooth on the Swiftkey. There are instances when it crashes in the messaging app, but provides you a seamless typing experience. There are some limitations though - you won't be able to use it to input passwords or use the voice typing.
The renowned tracing works good in iOS as well. It features better tap typing and word prediction. However, the estate word prediction on Swiftkey makes Swipe a bit dwarfer in comparison.
Developed by Touchpal technologies, it has stickers as a added attraction. It does everything fine right from tracing, typing, emojis and word prediction.
Fleskey has the best auto correct support. It supports gestures for word deletion and a couple of other tasks. There is no tracing (what you call swipe) though, so it may not interest you.
5. Adaptxt keyboard
It has support for everything you want to - emoji, word prediction, tracing and themes. But the auto correct feature is not much reliable.
Live....and Let Live!