Like Lew, I have little experience with the interface on iPhones. I only play on PC.
I feel I must reply to Lew, though, directly, as I have to challenge the Trap Bobber as the best. Yes, fish get away less when your bar isn't on them, but the Cork Bobber. Increase that fishing bar size so that you're able to keep it on the fish better. In the end, I think you'll catch the same amount of fish either way, but with the Cork Bobber, I think you'll end up with more higher quality fish. (You can only get iridium quality fish with a perfect catch or a quality bobber, but the quality bobber doesn't make it any easier to catch the fish.)
With an iridium rod, cork bobber, seafoam pudding (possibly seasoned seafoam pudding) and something from late-game content (called the Master enchantment which gives your fishing pole a +1 to fishing), I can catch any fish in the game. Even legendary fish only take a couple tries... and my wife is even better at the fishing mini-game than I am. Some tricks of the game I have down better than her, but she's overall better than I, and I can still catch anything in the game with this setup.