Treadle turns your iPhone into a fluid, two-axis MIDI expression controller for any instrument that listens to MIDI CC. Drag your finger up and down to send continuous expression (default CC 11). Glide left and right to add vibrato on a second CC (default CC 1 / Mod Wheel) — exactly what SWAM and Audio Modeling instruments expect for breath, bow pressure, and vibrato depth. One thumb, two expressive dimensions, in real time. BUILT FOR EXPRESSIVE PLAYING • Vertical axis → any CC you choose (expression, volume, breath, filter…) • Horizontal axis → a second independent CC for vibrato or modulation • Per-axis min/max range and response curve, so the full screen maps to exactly the range you want • Invert, channel select (1–16), and any CC number 0–127 CONNECTS TO EVERYTHING • Bluetooth MIDI — connect to a BLE pedal/synth, or advertise your iPhone so a Mac/iPad can connect to it • Appears as a virtual MIDI source ("Treadle") to other apps on the device • Send to all destinations or pick one • Works over USB and network MIDI too DESIGNED TO STAY OUT OF THE WAY • Full-screen control surface, status bar hidden • Optional on-screen position indicator • Two-finger tap (or the gear) for settings • Optional debug overlay showing live values, CC, channel, and destinations Perfect for SWAM woodwinds, brass and strings, expressive synth patches, and any rig where you need smooth, hands-on continuous control without reaching for a hardware pedal. SWAM is a trademark of Audio Modeling S.r.l. Treadle is an independent app and is not affiliated with, endorsed by, or sponsored by Audio Modeling.