title: React Native - RCT_EXPORT_VIEW_PROPERTY is nil in view init method
body: <p>I am trying to create a Native UI component on my RN project on iOS.
  I pass a props <code>uri</code> to my Native component. But when I try to use it in the <code>init</code> method of my view, it is <code>nil</code>.</p>
  
  <pre><code>// myNativeComponentManager.m
  
  @implementation myNativeComponentManager
  
  RCT_EXPORT_MODULE()
  RCT_EXPORT_VIEW_PROPERTY(uri, NSString *);
  
  - (UIView *)view
  {
      return [[myNativeComponentView alloc] init];
  }
  
  @end
  
  // myNativeComponentView.m
  
  @implementation myNativeComponentView
  
  - (instancetype)init
  {
      self = [super init];
  
  // self.uri is nil here
      NSURL *imageURL = [NSURL URLWithString:self.uri];
      NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
      UIImage *image = [UIImage imageWithData:imageData];
  
      self.imgView = [[UIImageView alloc] initWithFrame:self.bounds];
      self.imgView.image = image;
      self.imgView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
      self.imgView.userInteractionEnabled = YES;
      [self addSubview:self.imgView];
  
      UITapGestureRecognizer *tap =
      [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onTap:)];
      [self.imgView addGestureRecognizer:tap];
  
      return self;
  }
  
  - (void)onTap:(id)sender {
  // self.uri is not nil here
      NSLog(self.uri);
  }
   @end
  </code></pre>
  
  <p><code>uri</code> is <code>nil</code> in the <code>init</code> but not in the <code>onTap</code> method so it makes me think we can't use property in the init method? In that case, how do I initialise my image with this uri? Is there a way to know the view did initialized? I thought about creating a method to set my image and calling it on the JS part in <code>componentDidMount</code> but it feels wrong.</p>
  
  <p>Thanks for your help!</p>