React setstate嵌套对象问题

this.setState(prevState => ({
  nestedObject: {
    ...prevState.nestedObject,
    keyToUpdate: newValue
  }
}));

this.setState(prevState => ({
  nestedObject: Object.assign({}, prevState.nestedObject, {
    keyToUpdate: newValue
  })
}));

this.setState(prevState => {
  const updatedNestedObject = { ...prevState.nestedObject };
  updatedNestedObject.keyToUpdate = newValue;
  return { nestedObject: updatedNestedObject };
});

class MyComponent extends React.Component {
  state = {
    user: {
      name: 'John',
      address: {
        city: 'New York',
        zip: '10001'
      }
    }
  };

  updateCity = () => {
    this.setState(prevState => ({
      user: {
        ...prevState.user,
        address: {
          ...prevState.user.address,
          city: 'Los Angeles'
        }
      }
    }));
  };

  render() {
    return (
      <div>
        <p>{this.state.user.address.city}</p>
        <button onClick={this.updateCity}>Change City</button>
      </div>
    );
  }
}