What is iOS URL scheme hijacking and how do Universal Links provide a more secure alternative?

• A.C) iOS prevents URL scheme conflicts by rejecting App Store submissions with duplicate schemes; no two App Store apps can share the same scheme.
• B.B) URL scheme hijacking requires the malicious app to be installed before the legitimate app; installing the legitimate app first prevents all hijacking.
• C.A) Multiple iOS apps can register the same custom URL scheme (e.g., twitter://); when the scheme is invoked the OS picks one of the registered apps, potentially the malicious one. Universal Links use HTTPS domain-based routing with an apple-app-site-association (AASA) file hosted on the developer's domain; only the verified app for that domain can claim the link, because Apple validates the AASA file signature during app installation.