Use View Modifier instead of new view type for indicator, simplify the code

Author: dreampiggy

SDWebImageSwiftUI/Classes/Indicator/Indicator.swift

@@ -23,16 +23,15 @@ public struct Indicator<T> where T : View {
     }
 }
 
-/// A implementation detail View with indicator
+/// A implementation detail View Modifier with indicator
 /// SwiftUI View Modifier construced by using a internal View type which modify the `body`
 /// It use type system to represent the view hierarchy, and Swift `some View` syntax to hide the type detail for users
-struct IndicatorView<T, Content> : View where T : View, Content : View {
+struct IndicatorViewModifier<T> : ViewModifier where T : View {
     @ObservedObject var imageManager: ImageManager
 
     var indicator: Indicator<T>
-    var content: Content
 
-    var body: some View {
+    func body(content: Content) -> some View {
         if (imageManager.image != nil) && !imageManager.isLoading {
             // Disable Indiactor
             return AnyView(content)
@@ -46,12 +45,6 @@ struct IndicatorView<T, Content> : View where T : View, Content : View {
             )
         }
     }
-    
-    public init(_ view: Content, indicator: Indicator<T>, imageManager: ImageManager) {
-        self.content = view
-        self.indicator = indicator
-        self.imageManager = imageManager
-    }
 }
 
 #if os(macOS) || os(iOS) || os(tvOS)

SDWebImageSwiftUI/Classes/WebImage.swift

@@ -138,7 +138,7 @@ extension WebImage {
     /// Associate a indicator when loading image with url
     /// - Parameter indicator: The indicator type, see `Indicator`
     public func indicator<T>(_ indicator: Indicator<T>) -> some View where T : View {
-        return IndicatorView(self, indicator: indicator, imageManager: imageManager)
+        return self.modifier(IndicatorViewModifier(imageManager: imageManager, indicator: indicator))
     }
 
     /// Associate a indicator when loading image with url, convenient method with block