Can I make dynamic styles in React Native?

If you still want to take advantage of StyleSheet.create and also have dynamic styles, try this out:

const Circle = ({initial}) => {


const initial = user.pending ? user.email[0] : user.firstName[0];

    const colorStyles = {
        backgroundColor: randomColor()
    };

    return (
        <View style={[styles.circle, colorStyles]}>
            <Text style={styles.text}>{initial.toUpperCase()}</Text>
        </View>
    );
};

const styles = StyleSheet.create({
    circle: {
        height: 40,
        width: 40,
        borderRadius: 30,
        overflow: 'hidden'
    },
    text: {
        fontSize: 12,
        lineHeight: 40,
        color: '#fff',
        textAlign: 'center'
    }
});

Notice how the style property of the View is set as an array that combines your stylesheet with your dynamic styles.

Yes you can and actually, you should use StyleSheet.create to create your styles.

import React, { Component } from 'react';
import {
    StyleSheet,
    Text,
    View
} from 'react-native';    

class Header extends Component {
    constructor(props){
        super(props);
    }    

    render() {
        const { title, style } = this.props;
        const { header, text } = defaultStyle;
        const combineStyles = StyleSheet.flatten([header, style]);    

        return (
            <View style={ combineStyles }>
                <Text style={ text }>
                    { title }
                </Text>
            </View>
        );
    }
}    

const defaultStyle = StyleSheet.create({
    header: {
        justifyContent: 'center',
        alignItems: 'center',
        backgroundColor: '#fff',
        height: 60,
        paddingTop: 15,
        shadowColor: '#000',
        shadowOffset: { width: 0, height: 3 },
        shadowOpacity: 0.4,
        elevation: 2,
        position: 'relative'
    },
    text: {
        color: '#0d4220',
        fontSize: 16
    }
});    

export default Header;

And then:

<Header title="HOME" style={ {backgroundColor: '#10f1f0'} } />

I usually do something along the lines of:

<View style={this.jewelStyle()} />

...

jewelStyle = function(options) {
   return {
     borderRadius: 12,
     background: randomColor(),
   }
 }

Every time View is rendered, a new style object will be instantiated with a random color associated with it. Of course, this means that the colors will change every time the component is re-rendered, which is perhaps not what you want. Instead, you could do something like this:

var myColor = randomColor()
<View style={jewelStyle(myColor)} />

...

jewelStyle = function(myColor) {
   return {
     borderRadius: 10,
     background: myColor,
   }
 }