How come on Iphone there's only a keyboard?

I mean how come they don't employ that line thingy android uses? This freaking key board is so small typing is annoying because i have to keep going back to correct something when my sausage thumbs hit the wrong letter. No, auto correct makes things worse

Apple is very controlling on how your phone works. Apple decides that their keyboard is the keyboard your IPhone should be using so there's no way to really customize IPhone.

Unlike Apple devices, Android devices run on an open environment so you can personalize your Android phone. This means that they are a bunch of keyboards that you can choose to use that might include the swpying feature that you mentioned. So until Apple decides to include a swpying feature into their IPhone keyboards in a future IOS update, the own way to get that is by jailbreaking your phone.