Custom appsDefaults NSDictionary - ios

Question

I am trying to setup react-native application but I got stuck doing really basic changes to AooDekegate.m file. I have no experience in xCode. I have no idea what am I doing.
I was following this tutorial http://www.proreactnative.com/How-to-Develop-iOS-Apps-on-Linux-Using-React-Native/ . I got stuct doing Edit AppDelegate.m.
Could you please help me out?
This is my code:
/** * Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
#import "AppDelegate.h"
#import <React/RCTBundleURLProvider.h>
#import <React/RCTRootView.h>
#implementation AppDelegate
NSDictionary *appDefaults = #{ // ERROR !! Initializer element is not a compile-time constant
#"host_preference": #"localhost",
#"port_preference": #"8081",
};
[[NSUserDefaults standardUserDefaults] registerDefaults:appDefaults]; // ERROR !! Expected ']'
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSURL *jsCodeLocation;
NSString *host = [[NSUserDefaults standardUserDefaults] stringForKey: #"host_preference"];
NSString *port = [[NSUserDefaults standardUserDefaults] stringForKey: #"port_preference"];
NSString * urlString = [NSString stringWithFormat: #"http://%#:%#/index.ios.bundle?platform=ios&dev=true", host, port];
jsCodeLocation = [NSURL URLWithString: urlString];
RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
moduleName:#"AwesomeProject"
initialProperties:nil
launchOptions:launchOptions];
rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
UIViewController *rootViewController = [UIViewController new];
rootViewController.view = rootView;
self.window.rootViewController = rootViewController;
[self.window makeKeyAndVisible];
return YES;
}
#end

Answer 1

you do initialize a data object outside of a function, which would be fine for certain types.
In this case, I would rather declare the given values as constants or simply in the method that makes use of your variables:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSDictionary *appDefaults = #{
#"host_preference": #"localhost",
#"port_preference": #"8081",
};
[[NSUserDefaults standardUserDefaults] registerDefaults:appDefaults];
// Rest of your code
...
}
In addition:
If you do not need these values later on again (I don't know the react native framework in detail). You don't have to use NSUserDefaults for this. (NSUserDefaults are an attempt to persist data for the application).
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
NSURL *jsCodeLocation;
NSString *host = #"localhost";
NSString *port = #"8081";
NSString * urlString = [NSString stringWithFormat: #"http://%#:%#/index.ios.bundle?platform=ios&dev=true", host, port];
jsCodeLocation = [NSURL URLWithString: urlString];
RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation
moduleName:#"AwesomeProject"
initialProperties:nil
launchOptions:launchOptions];
rootView.backgroundColor = [[UIColor alloc] initWithRed:1.0f green:1.0f blue:1.0f alpha:1];
self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
UIViewController *rootViewController = [UIViewController new];
rootViewController.view = rootView;
self.window.rootViewController = rootViewController;
[self.window makeKeyAndVisible];
return YES;
}