Merge pull request alibaba#397 from mewehk/master

fix iOS 14 beta 4 crash

Author: H. Li

Source/ExtendCustomModelType.swift

@@ -74,13 +74,11 @@ fileprivate func assignProperty(convertedValue: Any, instance: _ExtendCustomMode
 
 fileprivate func readAllChildrenFrom(mirror: Mirror) -> [(String, Any)] {
     var children = [(label: String?, value: Any)]()
-    let mirrorChildrenCollection = AnyRandomAccessCollection(mirror.children)!
-    children += mirrorChildrenCollection
+    children += mirror.children
 
     var currentMirror = mirror
     while let superclassChildren = currentMirror.superclassMirror?.children {
-        let randomCollection = AnyRandomAccessCollection(superclassChildren)!
-        children += randomCollection
+        children += superclassChildren
         currentMirror = currentMirror.superclassMirror!
     }
     var result = [(String, Any)]()