gulpfile.js

'use strict';

var files = [
    'app/*.{js,xml,css}',
    'app/**/*.{js,xml,css}'
];

var emulator = 'iPhone-5'; // Default emulator

var validEmulators = [
    'iPhone-4s',
    'iPhone-5',
    'iPhone-5s',
    'iPhone-6-Plus',
    'iPhone-6',
    'iPad-2',
    'iPad-Retina',
    'iPad-Air',
    'Resizable-iPhone',
    'Resizable-iPad'
];

var gulp = require('gulp-param')(require('gulp'), process.argv);
var spawn = require('child_process').spawn;
var gutil = require('gulp-util');

gulp.task('default', function(device) {
    if (device !== null) {
        if (validEmulators.indexOf(device) === -1) {
            console.log();
            console.log(gutil.colors.red('Error!'));
            console.log(gutil.colors.red('"' + device + '" did not match a valid device'));
            console.log('Valid devices are: ' + validEmulators.join(', '));
            console.log();
            return true;
        } else {
            emulator = device;
        }
    }

    console.log();
    console.log(gutil.colors.blue('Watcher started, will restart emulator "' + emulator + '" when files change'));
    console.log('Tip: Run "gulp help" to show help');
    console.log();

    gulp.watch(files, function() {
        var child = spawn('tns', ['emulate', 'ios', '--device', emulator], {cwd: process.cwd()});
        var stdout = '';
        var stderr = '';

        child.stdout.setEncoding('utf8');
        child.stdout.on('data', function (data) {
            stdout += data;
            console.log(data);
        });

        child.stderr.setEncoding('utf8');
        child.stderr.on('data', function (data) {
            stderr += data;
            gutil.log(gutil.colors.red(data));
            gutil.beep();
        });

        child.on('close', function(code) {
            console.log('Done with exit code', code);
        });


    });
});

gulp.task('help', function() {
    console.log();
    console.log();
    console.log('    gulp               - run to start watching files and restart');
    console.log('                         default emulator (' + emulator + ') when files change.');
    console.log();
    console.log('    gulp -d <device>   - run with specific emulator.');
    console.log('                         Valid emulators are: ' + validEmulators.join(', '));
    console.log();
    console.log();
});



//tns emulate ios --device iPhone-6