title: No difference between Thin & Light fontWeight on iOS when adding custom font to my react-native app
body: <p>I just added a custom font to my react-native app (<a href="https://fonts.google.com/specimen/Josefin+Sans" rel="noreferrer">https://fonts.google.com/specimen/Josefin+Sans</a>).</p>
  
  <pre><code>JosefinSans-Bold.ttf
  JosefinSans-BoldItalic.ttf
  JosefinSans-Italic.ttf
  JosefinSans-Light.ttf
  JosefinSans-LightItalic.ttf
  JosefinSans-Regular.ttf
  JosefinSans-SemiBold.ttf
  JosefinSans-SemiBoldItalic.ttf
  JosefinSans-Thin.ttf
  JosefinSans-ThinItalic.ttf
  </code></pre>
  
  <p>I linked the font files by running <code>react-native link</code> after adding</p>
  
  <pre><code>"rnpm": {
    "assets": [
      "path/to/my/font/files"
    ]
  },
  </code></pre>
  
  <p>to my <code>package.json</code></p>
  
  <p>I then use the font in my app like so:</p>
  
  <pre><code>customFont: {
      fontFamily: 'Josefin Sans',
  },
  thin: {
      fontWeight: '100'
  },
  light: {
      fontWeight: '300'
  },
  semiBold: {
      fontWeight: '600'
  },
  bold: {
      fontWeight: '700'
  },
  italic: {
      fontStyle: 'italic'
  },
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/IYLE4.png" rel="noreferrer">iOS simulator screenshot of the different fontWeight and fontStyle</a></p>
  
  <p>The problem is that there is no difference between the <code>thin(fontWeight: '100')</code> &amp; the <code>light(fontWeight: '300')</code>.</p>
  
  <p>What I've tried so far:</p>
  
  <ul>
  <li>Tried with another font from google fonts (same problem).</li>
  <li>Tried to run the app on an actual device (rather than the simulator) but in vain.</li>
  <li>Tried to use iOS default font with those fontWeights: <code>thin</code> and <code>light</code> are really recognizable</li>
  <li>Displayed the font actual names (<code>JosefinSans-Light</code> and <code>JosefinSans-Thin</code>) in xcode with:</li>
  </ul>
  
  <p>_</p>
  
  <pre><code>for (NSString* family in [UIFont familyNames])
  {
    NSLog(@"%@", family);
    for (NSString* name in [UIFont fontNamesForFamilyName: family])
    { NSLog(@"  %@", name); }
  }
  </code></pre>
  
  <p>Has anybody had the same issue ?
  Any ideas on how to fix it and display the actual thin and light font weights ?</p>
  
  <p>Thanks a lot </p>