Fix the indicator will create multiple times, only create once with binding

Author: dreampiggy

SDWebImageSwiftUI/Classes/Indicator/Indicator.swift

@@ -29,7 +29,7 @@ public struct Indicator<T> where T : View {
 struct IndicatorViewModifier<T> : ViewModifier where T : View {
     @ObservedObject var imageManager: ImageManager
 
-    var indicator: Indicator<T>
+    let indicatorView: T
 
     func body(content: Content) -> some View {
         if (imageManager.image != nil) && !imageManager.isLoading {
@@ -40,11 +40,17 @@ struct IndicatorViewModifier<T> : ViewModifier where T : View {
             return AnyView(
                 ZStack {
                     content
-                    indicator.builder($imageManager.isLoading, $imageManager.progress)
+                    indicatorView
                 }
             )
         }
     }
+    
+    init(imageManager: ImageManager, indicator: Indicator<T>) {
+        self.imageManager = imageManager
+        // This syntax looks not Swifty, hope for SwiftUI better design
+        self.indicatorView = indicator.builder(_imageManager.projectedValue.isLoading, _imageManager.projectedValue.progress)
+    }
 }
 
 #if os(macOS) || os(iOS) || os(tvOS)