add: support responsive design for iPhone specially

Author: wang_liang

README.md

@@ -1,7 +1,7 @@
 #  The missing CSS-like module for SwiftUI
 > Check out the [example project using SwiftUI-CSS](https://github.com/hite/SwiftUI-CSS_example);
 > Also, Swift Package availble which url is `https://github.com/hite/SwiftUI-CSS`
-
+> Supported macOS(.v10_14), .iOS(.v13)
 The SwiftUI is a great UI development framework for the iOS app. After I wrote some to-be-released app with SwiftUI framework, I realized that I need a solution to write more clear, simple, view-style-decoupled code with lots of custom style design.
 
 So here is **SwiftUI-CSS**. With **SwiftUI-CSS**, you can:
@@ -162,7 +162,15 @@ let fontStyle = CSSStyle([.font(.caption)])
         let finalStyle = fontStyle + colorStyle
         print("finalStyle = \(finalStyle)")
 ```
-5. (to be continued)
-
+5. use responsive class to make view larger on larger screen
+```swift
+// In iOS, if the sketch file designed for screen 375x667, the responsive fator should be compared to UIScreen.main.bounds.size.width.
+let responsive = Responsive(UIScreen.main.bounds.size.width / 375)
+let wikiDesc_clsName = CSSStyle([
+    .font(Font.system(size: responsive.r(12))),
+    .foregroundColor(NormalDescColor)
+    .paddingEdges([.bottom], responsive.r(10))
+])
+```
 
 

Sources/SwiftUI_CSS/Responsive.swift

@@ -0,0 +1,43 @@
+//
+//  File.swift
+//  
+//
+//  Created by hite on 2020/11/3.
+//
+
+import Foundation
+import Combine
+import SwiftUI
+
+class Responsive: ObservableObject {
+    /// For example. the size of view in sketch file designed for iPhone 6 should larger  on iPhone by 1.104 ( 414 / 375) times.
+    /// so the factor = 1.104
+    @Published var factor: CGFloat
+    
+    init(_ factor: CGFloat) {
+        self.factor = factor
+    }
+    convenience init(designSize: CGRect) {
+        var factor: CGFloat = 1
+        if designSize.equalTo(.zero) {
+            factor = 1
+        } else {
+            #if os(iOS)
+            // Code specific to iOS
+            let size = UIScreen.main.bounds.size
+            factor = size.width / designSize.width
+            #elseif os(macOS)
+            // Code specific to macOS
+            factor = 1// maybe 1 is not right number.
+            #else
+            factor = 1
+            #endif
+        }
+        
+        self.init(factor)
+    }
+    
+    public func r(_ standardSize: CGFloat) -> CGFloat {
+        return self.factor * standardSize
+    }
+}

Sources/SwiftUI_CSS/SwiftUI_CSS.swift

@@ -205,7 +205,7 @@ extension View {
     }
 
     func changeClassName(_ clsName: CSSStyle) -> some View {
-        // 省略
+        //
         return self
     }