Building a cryptocurrency application for iOS today is fundamentally different from shipping a regular fintech product. The stakes are existential. A leaked seed phrase, a sloppy network call, or a single overlooked dependency can drain a user's life savings in seconds — and unlike a credit card chargeback, that money is gone forever. The blockchain doesn't issue refunds. The numbers paint a stark picture. According to Chainalysis, more than $2.17 billion was stolen from cryptocurrency services in just the first half of 2025 — already eclipsing the entirety of 2024. If the trend continues, total theft could surpass $4 billion by year's end, breaking the previous record set in 2022. Personal wallet compromises now make up roughly 23% of all stolen-fund activity, meaning the attack surface has shifted decisively toward end users — and toward the mobile apps they trust to hold their assets.…