HabitStreak implements evidence-based habit-tracking principles with a clean SwiftUI interface designed for iOS 16 and above. CORE MECHANICS β’ Streak Engine: calculates current streak by walking back consecutive completed days from today; resets on any missed day β’ Best Streak: all-time record of the longest unbroken consecutive sequence per habit β’ Completion Rate: 7-day and 30-day rolling window ratios displayed per habit and aggregated HABIT CONFIGURATION | Parameter | Options | |-------------|----------------------------------| | Frequency | Daily / Weekdays / Weekly | | Icon | 10 SF Symbols (drop, book, flameβ¦)| | Color | 7 preset hex colors | | Name | Free-text, any length | STATISTICS MODULE β’ Overview dashboard: total habit count, today's completions, 7-day aggregate success rate β’ Per-habit detail: current streak, best streak, 14-day tile visualization, 30-day completion count DATA LAYER β’ Persistence: UserDefaults with JSON encoding (Codable structs) β’ No network calls β fully offline β’ No account, no analytics, no third-party SDKs INTERFACE β’ SwiftUI-native, supports Dynamic Type β’ System-aware Light/Dark theme β’ Localized in English and Simplified Chinese β’ Tab navigation: Habits / Stats / Settings PRIVACY Zero data leaves the device. Deletion of the app permanently removes all habit data.