[ios] Update Facebook button disabled state, refactoring

iphone/Maps/Categories/UIColor+MapsMeColor.h

@@ -55,6 +55,8 @@
 + (BOOL)isNightMode;
 
 - (UIColor *)opposite;
-- (UIColor *)colorByBlendingWithColor:(UIColor * _Nonnull)color;
+
++ (UIColor *)facebookButtonBackground;
++ (UIColor *)facebookButtonBackgroundDisabled;
 
 @end

iphone/Maps/Categories/UIColor+MapsMeColor.mm

@@ -378,26 +378,11 @@ UIColor * color(SEL cmd)
 #pragma clang diagnostic pop
 }
 
-- (UIColor *)colorByBlendingWithColor:(UIColor *)color {
-  CGFloat bgR;
-  CGFloat bgG;
-  CGFloat bgB;
-  CGFloat bgA;
-  
-  CGFloat fgR;
-  CGFloat fgG;
-  CGFloat fgB;
-  CGFloat fgA;
-  
-  [self getRed:&bgR green:&bgG blue:&bgB alpha:&bgA];
-  [color getRed:&fgR green:&fgG blue:&fgB alpha:&fgA];
-  
-  CGFloat r = fgA * fgR + (1 - fgA) * bgR;
-  CGFloat g = fgA * fgG + (1 - fgA) * bgG;
-  CGFloat b = fgA * fgB + (1 - fgA) * bgB;
-  
-  return [UIColor colorWithRed:r green:g blue:b alpha:bgA];
++ (UIColor *)facebookButtonBackground {
+  return [UIColor colorWithRed:scaled(59) green:scaled(89) blue:scaled(152) alpha:alpha100];
 }
 
-
++ (UIColor *)facebookButtonBackgroundDisabled {
+  return [self.facebookButtonBackground colorWithAlphaComponent:.7];
+}
 @end

iphone/Maps/Categories/UIColor+Modifications.swift

@@ -1,4 +1,25 @@
 extension UIColor {
+  func blending(with color: UIColor) -> UIColor {
+    var bgR: CGFloat = 0
+    var bgG: CGFloat = 0
+    var bgB: CGFloat = 0
+    var bgA: CGFloat = 0
+    
+    var fgR: CGFloat = 0
+    var fgG: CGFloat = 0
+    var fgB: CGFloat = 0
+    var fgA: CGFloat = 0
+    
+    self.getRed(&bgR, green: &bgG, blue: &bgB, alpha: &bgA)
+    color.getRed(&fgR, green: &fgG, blue: &fgB, alpha: &fgA)
+    
+    let r = fgA * fgR + (1 - fgA) * bgR
+    let g = fgA * fgG + (1 - fgA) * bgG
+    let b = fgA * fgB + (1 - fgA) * bgB
+    
+    return UIColor(red: r, green: g, blue: b, alpha: bgA)
+  }
+
   func lighter(percent: CGFloat) -> UIColor {
     return colorWithBrightnessFactor(factor: 1 + percent)
   }

iphone/Maps/UI/Authorization/AuthorizationViewController.swift

@@ -88,6 +88,8 @@ final class AuthorizationViewController: MWMViewController {
       facebookButton.layer.cornerRadius = 8
       facebookButton.clipsToBounds = true
       facebookButton.titleLabel?.font = UIFont.bold14()
+      facebookButton.setBackgroundColor(UIColor.facebookButtonBackground(), for: .normal)
+      facebookButton.setBackgroundColor(UIColor.facebookButtonBackgroundDisabled(), for: .disabled)
       facebookButton.isEnabled = false
     }
   }