Measurements of CP observables in B± → DK± and B± → Dπ± decays are presented, where D represents a superposition of D0 and ¯D0 states. The D meson is reconstructed in the three-body final states K0 SK±π∓ and K0 SK∓π±. The analysis uses samples of B mesons produced in proton-proton collisions, corresponding to an integrated luminosity of 1.0, 2.0, and 6.0 fb−1 collected with the LHCb detector at centre-of-mass energies of √s = 7, 8, and 13 TeV, respectively. These measurements are the most precise to date, and provide important input for the determination of the CKM angle γ.