I have tried using electrum on android since I have android phone but never tried for ios and I think there is no ios version of electrum yet. Searched many times and never found one that is for iphone devices. As far as I know about electrum is that the lowest transaction fee is 3sat/byte and it's within 25 blocks.
Though Electrum isn't available in iOS platform you can use other wallets which are the most secured and lower fees wallets.Here you will find the best wallets for IOS with pros and corns
Best IOS Crypto Wallets 2020
TBH I already tried Green and mycelium but not satisfied 
Electrum is not available on iOS 
I will take a good look at Bread wallet
I think there is more options for IOS devices to use the best wallets.It will help you undoubtedly so here take a look Best IOS Crypto Wallets 2020 Electrum is not available on iOS I will take a good look at Bread wallet