Remove compatible system code for iOS8 and before (#23656)

Summary:
We already only support `iOS9+`, so we can remove all compatible codes now.

[iOS] [Fixed] - Remove compatible system code for iOS8 and before
Pull Request resolved: https://github.com/facebook/react-native/pull/23656

Differential Revision: D14224986

Pulled By: hramos

fbshipit-source-id: cac9ffe6788dd3eaf4f4f5f2b219f325ba78e85f

Libraries/Text/TextInput/Multiline/RCTUITextView.m

@@ -222,37 +222,12 @@ static UIColor *defaultPlaceholderColor()
 - (CGSize)sizeThatFits:(CGSize)size
 {
   // Returned fitting size depends on text size and placeholder size.
-  CGSize textSize = [self fixedSizeThatFits:size];
+  CGSize textSize = [super sizeThatFits:size];
   CGSize placeholderSize = self.placeholderSize;
   // Returning size DOES contain `textContainerInset` (aka `padding`).
   return CGSizeMake(MAX(textSize.width, placeholderSize.width), MAX(textSize.height, placeholderSize.height));
 }
 
-- (CGSize)fixedSizeThatFits:(CGSize)size
-{
-  // UITextView on iOS 8 has a bug that automatically scrolls to the top
-  // when calling `sizeThatFits:`. Use a copy so that self is not screwed up.
-  static BOOL useCustomImplementation = NO;
-  static dispatch_once_t onceToken;
-  dispatch_once(&onceToken, ^{
-    useCustomImplementation = ![[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){9,0,0}];
-  });
-
-  if (!useCustomImplementation) {
-    return [super sizeThatFits:size];
-  }
-
-  if (!_detachedTextView) {
-    _detachedTextView = [UITextView new];
-  }
-
-  _detachedTextView.attributedText = self.attributedText;
-  _detachedTextView.font = self.font;
-  _detachedTextView.textContainerInset = self.textContainerInset;
-
-  return [_detachedTextView sizeThatFits:size];
-}
-
 #pragma mark - Context Menu
 
 - (BOOL)canPerformAction:(SEL)action withSender:(id)sender

React/Base/RCTKeyCommands.m

@@ -14,11 +14,6 @@
 
 #if RCT_DEV
 
-static BOOL RCTIsIOS8OrEarlier()
-{
-  return [UIDevice currentDevice].systemVersion.floatValue < 9;
-}
-
 @interface RCTKeyCommand : NSObject <NSCopying>
 
 @property (nonatomic, strong) UIKeyCommand *keyCommand;
@@ -119,7 +114,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   // NOTE: throttle the key handler because on iOS 9 the handleKeyCommand:
   // method gets called repeatedly if the command key is held down.
   static NSTimeInterval lastCommand = 0;
-  if (RCTIsIOS8OrEarlier() || CACurrentMediaTime() - lastCommand > 0.5) {
+  if (CACurrentMediaTime() - lastCommand > 0.5) {
     for (RCTKeyCommand *command in [RCTKeyCommands sharedInstance].commands) {
       if ([command.keyCommand.input isEqualToString:key.input] &&
           command.keyCommand.modifierFlags == key.modifierFlags) {
@@ -171,7 +166,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
           // NOTE: throttle the key handler because on iOS 9 the handleKeyCommand:
           // method gets called repeatedly if the command key is held down.
-          if (RCTIsIOS8OrEarlier() || CACurrentMediaTime() - lastDoubleCommand > 0.5) {
+          if (CACurrentMediaTime() - lastDoubleCommand > 0.5) {
             command.block(key);
             lastDoubleCommand = CACurrentMediaTime();
           }
@@ -189,44 +184,14 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 
 @end
 
-@implementation UIApplication (RCTKeyCommands)
-
-// Required for iOS 8.x
-- (BOOL)RCT_sendAction:(SEL)action to:(id)target from:(id)sender forEvent:(UIEvent *)event
-{
-  if (action == @selector(RCT_handleKeyCommand:)) {
-    [self RCT_handleKeyCommand:sender];
-    return YES;
-  } else if (action == @selector(RCT_handleDoublePressKeyCommand:)) {
-    [self RCT_handleDoublePressKeyCommand:sender];
-    return YES;
-  }
-  return [self RCT_sendAction:action to:target from:sender forEvent:event];
-}
-
-@end
-
 @implementation RCTKeyCommands
 
 + (void)initialize
 {
-  if (RCTIsIOS8OrEarlier()) {
-
-    // swizzle UIApplication
-    RCTSwapInstanceMethods([UIApplication class],
-                           @selector(keyCommands),
-                           @selector(RCT_keyCommands));
-
-    RCTSwapInstanceMethods([UIApplication class],
-                           @selector(sendAction:to:from:forEvent:),
-                           @selector(RCT_sendAction:to:from:forEvent:));
-  } else {
-
-    // swizzle UIResponder
-    RCTSwapInstanceMethods([UIResponder class],
-                           @selector(keyCommands),
-                           @selector(RCT_keyCommands));
-  }
+  // swizzle UIResponder
+  RCTSwapInstanceMethods([UIResponder class],
+                         @selector(keyCommands),
+                         @selector(RCT_keyCommands));
 }
 
 + (instancetype)sharedInstance
@@ -254,17 +219,6 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 {
   RCTAssertMainQueue();
 
-  if (input.length && flags && RCTIsIOS8OrEarlier()) {
-
-    // Workaround around the first cmd not working: http://openradar.appspot.com/19613391
-    // You can register just the cmd key and do nothing. This ensures that
-    // command-key modified commands will work first time. Fixed in iOS 9.
-
-    [self registerKeyCommandWithInput:@""
-                        modifierFlags:flags
-                               action:nil];
-  }
-
   UIKeyCommand *command = [UIKeyCommand keyCommandWithInput:input
                                               modifierFlags:flags
                                                      action:@selector(RCT_handleKeyCommand:)];
@@ -306,17 +260,6 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 {
   RCTAssertMainQueue();
 
-  if (input.length && flags && RCTIsIOS8OrEarlier()) {
-
-    // Workaround around the first cmd not working: http://openradar.appspot.com/19613391
-    // You can register just the cmd key and do nothing. This ensures that
-    // command-key modified commands will work first time. Fixed in iOS 9.
-
-    [self registerDoublePressKeyCommandWithInput:@""
-                        modifierFlags:flags
-                               action:nil];
-  }
-
   UIKeyCommand *command = [UIKeyCommand keyCommandWithInput:input
                                               modifierFlags:flags
                                                      action:@selector(RCT_handleDoublePressKeyCommand:)];

React/Base/RCTMultipartDataTask.m

@@ -11,20 +11,6 @@
 
 @end
 
-// We need this ugly runtime check because [streamTask captureStreams] below fails on iOS version
-// earlier than 9.0. Unfortunately none of the proper ways of checking worked:
-//
-// - NSURLSessionStreamTask class is available and is not Null on iOS 8
-// - [[NSURLSessionStreamTask new] respondsToSelector:@selector(captureStreams)] is always NO
-// - The instance we get in URLSession:dataTask:didBecomeStreamTask: is of __NSCFURLLocalStreamTaskFromDataTask
-//   and it responds to captureStreams on iOS 9+ but doesn't on iOS 8. Which means we can't get direct access
-//   to the streams on iOS 8 and at that point it's too late to change the behavior back to dataTask
-// - The compile-time #ifdef's can't be used because an app compiled for iOS8 can still run on iOS9
-
-static BOOL isStreamTaskSupported() {
-  return [[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){9,0,0}];
-}
-
 @implementation RCTMultipartDataTask {
   NSURL *_url;
   RCTMultipartDataTaskCallback _partHandler;
@@ -52,9 +38,7 @@ static BOOL isStreamTaskSupported() {
   NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]
                                                         delegate:self delegateQueue:nil];
   NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:_url];
-  if (isStreamTaskSupported()) {
-    [request addValue:@"multipart/mixed" forHTTPHeaderField:@"Accept"];
-  }
+  [request addValue:@"multipart/mixed" forHTTPHeaderField:@"Accept"];
   NSURLSessionDataTask *dataTask = [session dataTaskWithRequest:request];
   [dataTask resume];
   [session finishTasksAndInvalidate];

React/Views/RCTFont.mm

@@ -142,19 +142,8 @@ static UIFont *cachedSystemFont(CGFloat size, RCTFontWeight weight)
     if (defaultFontHandler) {
       NSString *fontWeightDescription = FontWeightDescriptionFromUIFontWeight(weight);
       font = defaultFontHandler(size, fontWeightDescription);
-    } else if ([UIFont respondsToSelector:@selector(systemFontOfSize:weight:)]) {
-      // Only supported on iOS8.2 and above
-      font = [UIFont systemFontOfSize:size weight:weight];
     } else {
-      if (weight >= UIFontWeightBold) {
-        font = [UIFont boldSystemFontOfSize:size];
-      } else if (weight >= UIFontWeightMedium) {
-        font = [UIFont fontWithName:@"HelveticaNeue-Medium" size:size];
-      } else if (weight <= UIFontWeightLight) {
-        font = [UIFont fontWithName:@"HelveticaNeue-Light" size:size];
-      } else {
-        font = [UIFont systemFontOfSize:size];
-      }
+      font = [UIFont systemFontOfSize:size weight:weight];
     }
 
     {