What is the best DJ application for IPhone?
Good question but for me the answer is it depends on what you want to do!

Like on Android there are several types of applications, pads, synths, or mixers.
To help you make the choices we have made a selection of the best Android DJ applications.

DJ Pads

Novation Launchpad

Novation Launchpad is an application that lets you record and share music instantly on your iPad, simply by triggering and mixing sounds on rack. Also you can import your own sounds and start up to 8 loops both from a 8x6 grid (see image above). Being composed of 8 sliders and 8 volumes filters allowing you to apply powerful performance effects. Organize yourself with full access to a professional sound library. App designed exclusively for the iPad. Compatible with iOS 6, iOS 7, iPad2, iPad3, iPad4 and iPad Mini.

Synthesizers

iMiNi

iMini is a variant of classic Minimoog synthesizer 1971 ™ *, the most powerful of synthesizing created until today. Imini offers an exceptional level of sound quality on the iPad with a library of 500 professional sounds. You can manage a visible Keyboard control panel allows you to set octaves, scales, envelope modes and other settings.   Also thanks to Performance mode you have access to a multifunction arpeggiator and two assignable XY pads that provide real-time control over your sound very effectively. And Effects mode that gives you a wide choice, choir and Analog Delay of very high quality. App supports MIDI, WIST, iOS devices, office Mini V software for MAC and PC. Too bad it pays

The DJ Turntables / Mixer Tables

Touch DJ™ Evolution

Touch DJ Evolution innovates other DJ applications. Indeed instead of recreating any existing hardware DJ CD decks or trays as it offers a completely innovative and modern approach, giving the possibility of manipulation of the direct route. Moreover you have a mix is ​​100% visually, without any pre-registration with headphones. As for waveforms of the track they float in the field of futuristic glowing neon interface with the calculated beatmaps. Ease of use: a single setting in the beatmap box to activate the "1-Tap Auto-Sync", which will align the tracks perfectly. You have a very potent cocktail mix, with tracks still in phase, the key of the tracks does not change when the speed of the track is changed by pressing the key ("Key Lock") technology "Master Tempo". You have great opportunities to create ... Make the most creative blends quantified ... Earrings, 7 effects, sampler, automatic EQ, unlimited cue points.