Available on the App Store: https://apps.apple.com/us/app/impedance-converter/id6474902691
Impedance converter can convert between various commonly used representations of electrical impedance, be it magnitude and angle, resistance and reactance, and alternative forms such as admittance, or reflection coefficients. It also shows the impedance as a series or parallel circuit involving a resistor and a capacitor or inductor. And finally, it shows the impedance on a Smith chart, along with characterizations such as SWR, and wavelengths.
Each view of impedance can be edited (such as changing the value for the equivalent circuit capacitor, or moving the impedance point on the Smith chart), and the other representations for impedance will be updated in a live fashion.