Refactor BlurView to use modern Objective-C syntax and paradigms

This moves to modern Objective-C practices.

Synthesized properties now use property declarations in a private
category.

UIVisualEffectViews will now only be created once, rather than on each
change of blurType.

BlurAmount uses a class property to track the currently set amount.

ios/BlurAmount.h

@@ -1,7 +1,9 @@
 #import <UIKit/UIKit.h>
 
 @interface BlurAmount : UIBlurEffect
-+ (id)updateBlurAmount:(NSNumber*)blurAmount;
 
 @property (nonatomic, copy) NSNumber *blurAmount;
+
++ (id)updateBlurAmount:(NSNumber*)blurAmount;
+
 @end

ios/BlurAmount.m

@@ -2,13 +2,16 @@
 #import <objc/runtime.h>
 
 @interface UIBlurEffect (Protected)
+
 @property (nonatomic, readonly) id effectSettings;
+@property (nonatomic, copy, class) NSNumber *localBlurAmount;
+
 @end
 
 
 @implementation BlurAmount
 
-  NSNumber *localBlurAmount;
+static NSNumber *_localBlurAmount = nil;
 
 + (instancetype)effectWithStyle:(UIBlurEffectStyle)style
 {
@@ -21,7 +24,7 @@
 - (id)effectSettings
 {
     id settings = [super effectSettings];
-    [settings setValue:localBlurAmount forKey:@"blurRadius"];
+    [settings setValue:BlurAmount.localBlurAmount forKey:@"blurRadius"];
     return settings;
 }
 
@@ -32,9 +35,19 @@
     return result;
 }
 
++ (void)setLocalBlurAmount:(NSNumber *)localBlurAmount {
+    if (localBlurAmount != _localBlurAmount) {
+        _localBlurAmount = localBlurAmount;
+    }
+}
+
++ (NSNumber *)localBlurAmount {
+    return _localBlurAmount;
+}
+
 + (id)updateBlurAmount:(NSNumber*)blurAmount
 {
-    localBlurAmount = blurAmount;
+    self.localBlurAmount = blurAmount;
     return blurAmount;
 }
 

ios/BlurView.m

@@ -1,35 +1,43 @@
+#import <UIKit/UIKit.h>
 #import "BlurView.h"
 #import "BlurAmount.h"
 
+@interface BlurView ()
 
-@implementation BlurView {
-  UIVisualEffectView *_visualEffectView;
-  UIBlurEffect * blurEffect;
+@property (nonatomic, strong) UIVisualEffectView *visualEffectView;
+@property (nonatomic, strong) UIBlurEffect *blurEffect;
+
+@end
+
+@implementation BlurView
+
+- (instancetype)initWithFrame:(CGRect)frame {
+    if (self = [super initWithFrame:frame]) {
+        self.blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
+        self.visualEffectView = [[UIVisualEffectView alloc] initWithEffect:self.blurEffect];
+        self.visualEffectView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+        self.visualEffectView.frame = frame;
+
+        self.clipsToBounds = true;
+
+        [self addSubview:self.visualEffectView];
+    }
+
+    return self;
 }
 
 - (void)setBlurType:(NSString *)blurType
 {
-  if (_visualEffectView) {
-    [_visualEffectView removeFromSuperview];
-  }
-
-  self.clipsToBounds = true;
-  if ([blurType isEqual: @"xlight"]) {
-    blurEffect = [BlurAmount effectWithStyle:UIBlurEffectStyleExtraLight];
-  } else if ([blurType isEqual: @"light"]) {
-    blurEffect = [BlurAmount effectWithStyle:UIBlurEffectStyleLight];
-  } else if ([blurType isEqual: @"dark"]) {
-    blurEffect = [BlurAmount effectWithStyle:UIBlurEffectStyleDark];
-  } else {
-    blurEffect = [BlurAmount effectWithStyle:UIBlurEffectStyleDark];
-  }
-
-    dispatch_async(dispatch_get_main_queue(), ^{
-        _visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];
-        _visualEffectView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
-        _visualEffectView.frame = self.bounds;
-        [self insertSubview:_visualEffectView atIndex:0];
-    });
+    if ([blurType isEqual: @"xlight"]) {
+        self.blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleExtraLight];
+    } else if ([blurType isEqual: @"light"]) {
+        self.blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
+    } else if ([blurType isEqual: @"dark"]) {
+        self.blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
+    } else {
+        self.blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];
+    }
+    self.visualEffectView.effect = self.blurEffect;
 }
 
 - (void)setBlurAmount:(NSNumber *)blurAmount

ios/BlurViewManager.h

@@ -2,4 +2,4 @@
 
 @interface BlurViewManager : RCTViewManager
 
-@end
+@end