use chevron up/down icons in pre iOS13 as well

deltachat-ios/Assets.xcassets/ic_chevron_down.imageset/Contents.json

@@ -0,0 +1,23 @@
+{
+  "images" : [
+    {
+      "filename" : "arrows_bottom_chevron_direction_move_icon_1x.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "filename" : "arrows_bottom_chevron_direction_move_icon_2x.png",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "filename" : "arrows_bottom_chevron_direction_move_icon_3x.png",
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

deltachat-ios/Assets.xcassets/ic_chevron_up.imageset/Contents.json

@@ -0,0 +1,23 @@
+{
+  "images" : [
+    {
+      "filename" : "arrow_chevron_direction_down_move_icon_1x.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "filename" : "arrow_chevron_direction_down_move_icon_2x.png",
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "filename" : "arrow_chevron_direction_down_move_icon_3x.png",
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

deltachat-ios/Chat/Views/ChatSearchAccessoryBar.swift

@@ -31,8 +31,7 @@ public class ChatSearchAccessoryBar: UIView, InputItem {
             view.setImage(UIImage(systemName: "chevron.up"), for: .normal)
             view.tintColor = .systemBlue
         } else {
-            view.setTitle(String.localized("previous"), for: .normal)
-            view.setTitleColor(.systemBlue, for: .normal)
+            view.setImage(UIImage(named: "ic_chevron_up")?.sd_tintedImage(with: .systemBlue), for: .normal)
         }
         view.translatesAutoresizingMaskIntoConstraints = false
         view.isUserInteractionEnabled = true
@@ -47,8 +46,7 @@ public class ChatSearchAccessoryBar: UIView, InputItem {
             view.setImage(UIImage(systemName: "chevron.down"), for: .normal)
             view.tintColor = .systemBlue
         } else {
-            view.setTitle(String.localized("next"), for: .normal)
-            view.setTitleColor(.systemBlue, for: .normal)
+            view.setImage(UIImage(named: "ic_chevron_down")?.sd_tintedImage(with: .systemBlue), for: .normal)
         }
         view.translatesAutoresizingMaskIntoConstraints = false
         view.imageView?.contentMode = .scaleAspectFit