azamsharp · March 24, 2025 16:03 · Mar 24, 2025
diff --git a/ValidatePropertyWrapper.swift b/ValidatePropertyWrapper.swift
@@ -0,0 +1,142 @@
+//
+//  ContentView.swift
+//  ValidationDemo
+//
+//  Created by Mohammad Azam on 3/24/25.
+//
+
+import SwiftUI
+
+// Validation View Modifier
+struct ValidationModifier: ViewModifier {
+
+    let errorMessage: String?
+
+    func body(content: Content) -> some View {
+        VStack(alignment: .leading, spacing: 4) {
+            content
+
+            Text(errorMessage ?? "")
+                .font(.caption)       // Smaller text for error message
+                .foregroundColor(.red)
+                .frame(height: 20)    // Keep consistent height
+                .opacity(errorMessage == nil ? 0 : 1)  // Hide when no error
+                .animation(.easeInOut(duration: 0.2), value: errorMessage) // Smooth transition
+        }
+    }
+}
+
+extension View {
+    func withValidation(_ errorMessage: String?) -> some View {
+        self.modifier(ValidationModifier(errorMessage: errorMessage))
+    }
+}
+
+
+
+
+enum RegexExpression: String {
+    case email = #"^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}$"#
+}
+
+enum ValidationRule {
+    case required(String)
+    case regularExpression(RegexExpression, String)
+}
+
+@propertyWrapper
+struct Validate<T: Equatable> {
+
+    private var value: T
+    private var initialValue: T
+    private var rules: [ValidationRule]
+    private var isDirty = false
+
+    var wrappedValue: T {
+        get { value }
+        set {
+
+            if newValue != initialValue {
+                isDirty = true
+            }
+
+            value = newValue
+        }
+    }
+
+    var projectedValue: String? {
+
+        guard isDirty else { return nil }
+
+        for rule in rules {
+            if let message = validate(rule: rule) {
+                return message
+            }
+        }
+
+        return nil
+    }
+
+    private func validate(rule: ValidationRule) -> String? {
+
+        switch rule {
+            case .required(let message):
+                return validateRequired(message: message)
+            case .regularExpression(let regexExpression, let message):
+                return validateRegex(pattern: regexExpression.rawValue, message: message)
+        }
+    }
+
+    private func validateRequired(message: String) -> String? {
+
+        if let stringValue = value as? String, stringValue.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
+            return message
+        }
+
+        return nil
+    }
+
+    private func validateRegex(pattern: String, message: String) -> String? {
+        guard let stringValue = value as? String else { return nil }
+
+        let regex = try? NSRegularExpression(pattern: pattern, options: .caseInsensitive)
+        let range = NSRange(location: 0, length: stringValue.utf16.count)
+
+        return regex?.firstMatch(in: stringValue, options: [], range: range) == nil ? message : nil
+    }
+
+    init(wrappedValue: T, _ rules: ValidationRule...) {
+        self.value = wrappedValue
+        self.initialValue = wrappedValue
+        self.rules = rules
+    }
+
+}
+
+struct Customer {
+
+    @Validate(
+        .required("Email is required."),
+        .regularExpression(.email, "Email should be in correct format.")
+    )
+    var email: String = ""
+
+}
+
+struct ContentView: View {
+
+    @State private var customer = Customer()
+
+    var body: some View {
+        VStack {
+            TextField("Email", text: $customer.email)
+                .textFieldStyle(.roundedBorder)
+                .withValidation(customer.$email)
+        }
+        .padding()
+    }
+}
+
+#Preview {
+    ContentView()
+}
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