change reposity name & add post

Author: choru-k

README.md renamed to How_to_add_Firebase_Auth_with_react_native/README.md

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+# How to upload photo/file in react-native
+
+If you wanted to upload photo/file in react-native, almostly you have found many library such as [react-native-uploader](https://github.com/aroth/react-native-uploader) , [react-native-file-upload](https://github.com/booxood/react-native-file-upload). But I think easiest way is this post, not use library, not write native code, and anybody can understand. 
+
+# use fetch 
+
+Fetch supports `multipart/form-data`. You can upload your `formdata` like in webbrower. see [this](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch#Body)
+
+ ### example
+
+
+
+```jsx
+const data = new FormData();
+data.append('name', 'testName'); // you can append anyone.
+data.append('photo', {
+  uri: photo.uri,
+  type: 'image/jpeg', // or photo.type
+  name: 'testPhotoName'
+});
+fetch(url, {
+  method: 'post',
+  body: data
+}).then(res => {
+  console.log(res)
+});
+```
+
+only this. If you want many photos
+
+```js
+const photos = [photo1, photo2, ...]
+photos.forEach((photo) => {
+    data.append('photo', {
+    uri: photo.uri,
+    type: 'image/jpeg', // or photo.type
+    name: photos.name
+  });  
+});
+fetch(url, opts);
+
+```
+
+
+
+# How can I get photo from gallery?
+
+You can use [React Native API](https://facebook.github.io/react-native/docs/cameraroll.html), or other library such as [react-native-image-picker](https://github.com/marcshilling/react-native-image-picker),  [react-native-camera-roll-picker](https://github.com/jeanpan/react-native-camera-roll-picker). 
+
+#### Tips:
+
+In iOS+10, you must add 
+
+```xml
+ <key>NSPhotoLibraryUsageDescription</key>
+ <string> Why you want Photo? </string>
+```
+
+In Android, you must add
+
+```xml
+    <uses-permission android:name="android.permission.CAMERA" />
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
+    <uses-feature android:name="android.hardware.camera" android:required="false"/>
+    <uses-feature android:name="android.hardware.camera.autofocus" android:required="false"/>
+
+```
+
+
+
+# How can I add progress?
+
+Unfortunately, fetch doen't support progress. But we can use xhr which support progress.
+
+I make `api.js`
+
+```javascript
+const futch = (url, opts={}, onProgress) => {
+    console.log(url, opts)
+    return new Promise( (res, rej)=>{
+        var xhr = new XMLHttpRequest();
+        xhr.open(opts.method || 'get', url);
+        for (var k in opts.headers||{})
+            xhr.setRequestHeader(k, opts.headers[k]);
+        xhr.onload = e => res(e.target);
+        xhr.onerror = rej;
+        if (xhr.upload && onProgress)
+            xhr.upload.onprogress = onProgress; // event.loaded / event.total * 100 ; //event.lengthComputable
+        xhr.send(opts.body);
+    });
+}
+export default futch
+
+```
+
+Use this.
+
+### example
+
+```javascript
+import futch from './api';
+
+const data = new FormData();
+data.append('name', 'testName');
+data.append('photo', {
+  uri: source.uri,
+  type: 'image/jpeg',
+  name: 'testPhotoName'
+});
+
+
+futch(url, {
+  method: 'post',
+  body: data
+}, (progressEvent) => {
+  const progress = progressEvent.loaded / progressEvent.total;
+  console.log(progress);
+}).then((res) => console.log(res), (err) => console.log(err))
+```
+
+
+
+# Sample
+
+use react-native-image-picker and react-native-camera-roll-picker(based on React Native CameraRoll API). 
+
+## [Here](https://github.com/g6ling/react-native-fileUpload-example)
+