在安裝react-native-picker過(guò)程中，react-native link報(bào)錯(cuò)，且沒(méi)有任何錯(cuò)誤日志說(shuō)明錯(cuò)誤原因，導(dǎo)致運(yùn)行項(xiàng)目時(shí)出現(xiàn)undefined is not an object (evaluating 'Picker._init')的錯(cuò)誤。

網(wǎng)上找到了兩個(gè)解決方案：

https://github.com/beefe/react-native-picker/issues/289

https://github.com/beefe/react-native-picker/issues/294

綜合整理后，解決方案如下：

1.文件./android/settings.gradle中末尾添加：

include?':react-native-picker'
project(':react-native-picker').projectDir?=?new?File(rootProject.projectDir,?'../node_modules/react-native-picker/android')

2.文件./android/app/build.gradle的dependencies內(nèi)添加（注意其他行有逗號(hào)","，最后一行沒(méi)逗號(hào)）：

...
dependencies?{
????...
????compile?project(':react-native-picker')
}
...

3.文件./android/app/src/main/java/com/xxx/xxx/MainApplication.java中添加：

import?com.beefe.picker.PickerViewPackage;
...
????@Override
????protected?ListgetPackages()?{
??????return?Arrays.asList(
????????new?MainReactPackage(),
????????...
????????new?PickerViewPackage()
??????);
????}
...

4.重新運(yùn)行項(xiàng)目就OK了。