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Save person default

welcome back to another video today we're gonna be going over something that's pretty important that has been requested a couple of times and that is how to save and get data in your iOS app so for example if the user enters in some text and we want to get it and display back to the user when they come back to our app very very common functionality as you can imagine so we're gonna walk through that and talk about some best practices and how I personally like to do it and how I recommend you should do it so with that being said let's fire up Xcode and first and foremost if you could be so kind as to hit that like button it definitely helps out the video and it really helps me create more of these videos for you all so we're gonna choose a single V application we're gonna make sure we have Swift and storyboard down here call it whatever you'd like I'll just call it test save it wherever you want to save it in this case the desktop and give it a second cool so let's let's go ahead and close this drag this up here give yourself some room to work and let's run this application into any simulator which we'll see will have a white screen in just a second here but every time you run it obviously this will already be open for us so it'll make our lives a little faster cool so when we want to save something we need to save it into a location obviously so there's a couple of solutions that apple provides and also some third parties in terms of saving data and in this video in particular we're gonna be working with one of the simpler ones which is called user defaults and it's built into iOS it's built into the framework you don't have to include any library but for this demo actually what we're gonna do is like I mentioned we're gonna put a text field here and we're also gonna put a label here and what we're gonna do is when the user enters something into the text field and hits the enter key of the return key we'll save it and then we'll close the app and reopen it and we'll see the label shows the text that was previously saved if there was anything saved so obviously in the first time we opened the app there will be nothing there so before we have to talk about the saving let's go ahead and put a text field and a label here in our storyboard and link that up with a I B outlet so let's go ahead and make the background color something not white because it's not as fun so let's go with this blue and let's go and take a UI text field drag it on here and if you're not familiar with kind of dragging these user interface elements on here leave a comment I'll be more than happy to point you into into the direction of a video that I've done to explain this let's add some constraints to this so let's do 20 for the top 20 20 and let's also give it a height of 52 which should be good enough and then right below it we're gonna add a label which is where we're gonna actually display the text so to put that right there again we want to add some constraints so let's do 20 20 20 20 from the bottom so it'll be a big label and let's go in here and center our text and we're gonna do one line which means the text in our label will wrap onto unlimited lines as it needs to fill up to make sure the text isn't truncated with like the dot that you'll see in some apps with that being done this is all good to go we're gonna go to our view controller and create two outlets one for the label and one for the text field so we're gonna do this view controller we're gonna create two IV outlets and when it's gonna be a label and we're gonna just copy and paste this really fast and one is gonna be what's called a text field so this is just kind of like the setup for our example so no no data being saved yet so bear for me two seconds while we get this situated so we're gonna right-click on this and we'll drag from the field to the field and we'll drag from the label to the label which is this whole thing and then the last thing we're gonna do to actually set this up is once the user presses enter on the keyboard when they're typing in the field we want to save the data so ignoring the saving part we want to get that event when the person taps the return key and the way we're gonna do that is through a delegate function on the field if you're not familiar with the delegate notion that's okay it's irrelevant for this video but you can just follow along so we're gonna say the delegate for this field of self and what we're gonna add to this up here is UI text field delegate and the function we're interested in is should return and this returns a bool so we can return true so basically once the person presses the Enter key on the keyboard when they're typing in the field basically we're gonna come to this function and we're gonna do stuff in here so let's run this app with command R and we'll see we have our blue interface along with this text field up here and this label was just as label right now is the initial text cool so let's talk about actually saving data so like I mentioned we're gonna be working with user defaults user defaults is more or less a dictionary so you think of it as you can save things with the key and the actual thing you save is the value for that key so for example if we want to save a high score maybe we make the key a score and what we're saving into it is a string of the actual value so it's 100 in this case what we're gonna do is actually something a little more in tune with our example that we've painted out with the interface so we're gonna save a person's name it's gonna be something like John for example so whatever the user types into the field is what will save so the way we do this is very very simple so first and foremost we need to create an instance of our user defaults so let's call this user defaults to make it a little more obvious what it is and it's an instance of this user default class so like that to save something it's actually very very simple we're just gonna on this on this instance all we're gonna do is we're gonna say set value for key so you can notice there's a couple in here so let's go through these so you can notice we can set a value sum which is any and the key is always a string we can also do things like set a bull sorry one second let's see I see so what we can do is so they've recently changed instance with five actually in the actual value because it doesn't have to be a string we see it's any optional we can set an integer we can sent a set an object we can set a boolean so like true or false more or less you can set pretty much anything we can see down here we can set numbers and other things as well so the notion of user defaults is more or less to save smaller bits of information so if you think it's something like a larger app like the Instagram app or the Facebook app where we would want to maybe save like the last few pictures that the person is seen or something larger user defaults isn't really the appropriate place for that for something like that we would use things like core data or a whole database on board like realm that I'll probably do a follow up video on but it's important to understand the user default it's very lightweight and is meant to be used for simple tasks so with that being said let's actually save let's actually see the value in here whoops sorry no sets we want value for key let's make the key name and now we want to actually save the information that's in the feel of the person has typed in so we're just gonna say field dot text and that's basically all there is to it once the person presses the enter key we will save basically the the contents of the field so let's just run the app make sure that's good to go now we won't really know that the information that we've typed in here has been saved because we're not giving any feedback to the user but what we can do what we should do is let's actually dismiss the keyboard once we press the Enter key which I'm doing on my physical computer keyboard so let's do resign first responder on the field which basically tells the system to return the keyboard basically more or less dismissing it type in type in Jason cool so we know something's going on we're coming into this function and it is dismissing so now what we want to do is every time the this view controller loads let's go ahead and check if a value exists for this key and if it does let's update the label to have its text so what we can do is we can do similar to set value for key but we can do here is you can say user default value for key like so and we can actually even make this simpler and say the labels text is gonna be the value for this key so actually so this is giving us an error and I should probably explain why this is an error what we need to do to fix it because we can say any type of object as the value for the key a Swift doesn't know that this is per se going to be a string we know it because we've said it here but we need to unwrap this because it could be an optional and it could come back as a number or anything and the labels text has to be a string and what we can do in here now is this equals value so what we've essentially said here is if there is if there's a thing in here if there is a value for key we're gonna put it in value and we want it back as a string and we're gonna do ask question mark which basically says try to get this thing the value at this key as a string and if we get it it'll be stored into this value property and we're gonna say the labels text is now value so if you run this we'll see whatever the last thing was that I typed in which was Jason which we see right there so let's do this one more time so let's type in and now let's type in David press ENTER and let's close this and reopen it and we'll see we have David so that's a very very simple example of saving data and kind of fetching it again with user defaults it's super simple but what I want to go over is some good practices to use or user defaults and there's two in particular I want to cover so because user defaults are for your entire application in other words one app can not have multiple places where data is stored it's a good idea to initialize this object with a sweet name this object sorry about that user defaults with a sweet name and what this basically does is it provides a key to wherever this data is being safe in other words just sweet and this is very similar to your bundle ID so what people will often do and when I recommend you do as is convention is to give it something similar to your bundle identifier for your app if you're not familiar with bundle ID please leave a comment and we can go over it it's maybe something like that so this can more or less be anything at all any string but it's always a good idea to provide a sweet name if you're also creating things like an Apple watch app and you want to share data across different apps different targets rather in one project you can provide the sweet name and that ensures that your data is being saved for the proper location and with that being said the other thing that I wanted to mention very briefly in this video is it's often a good idea to have a separate standalone class that includes this user default object so for the sake of this demo what I'll do is I'll create another class down here and we'll call it I like to call it personal UDM for a user default manager or you can spell it out but we'll just call it you DM for the purposes of this video and the reason I do this is because you can what you can do is is create a variable in here which is a static constant and call it shared and have this be equal to your user defaults instance and you can provide other functions in here to do various things like let's say you save user passwords in here you save other things whatever your app requires you can create functions to get those things so you don't have to do this like if let nonsense and various view controllers and you'll just get a proper return object back from here but what this lets us do is in each class that we want to use this user default instead of creating a variable we can do this UD m dot shared which is what we called it if I'm not mistaken you know you can do this UD m dot shared but we need to create an instance of this actually so let's do so we can do you DM dot shared dot defaults and the reason it's not picking it up is because should I be picking it up let's see what's the error that we have over here so the error that we have over here is static member defaults cannot be used okay obviously these both can't be statics so this one actually needs to just be constant this is make sure that we're using this class as a singleton and I like to keep these little debug moments in the video for the sake of kind of explaining my thought process along the way and showing you guys how these errors get made and being able to read the errors understand it and fix it so let's see what else override func so we can get rid of this that's also why it's complaining which is good to go and the other error here is value optional type user defaults okay so what we can say it down here is so the create creating this with a sweet name returns an optional so we can create this default as equaling user defaults with a bang at the end which is a force unwrap and then it looks like this is good to go and lastly we can update this over here and that's good to go so let's actually review this cuz I ramble a little bit and had some air along the way so what we've essentially done is any view controller that wants to save read and write data what we can do is we can use as UTM shared defaults throughout our entire project our entire iOS app and we don't have to worry about doing things like putting a property on every single view controller called user defaults and it saves us boilerplate code it saves us a lot of duplicate code and just makes your life easier so I also mentioned you could do things like moving this if flat stuff into here so we could make a function that is like get name and this could return a string in other words we can abstract a lot of functionality into this class and clean up this type of stuff so yeah that's basically how you can save data and this is giving an error because it wants a string to be returned but this is basically how you can save data in an iOS after user defaults it's very very simple it's there's a lot of like trial and error of like what you need to save and I remember when I first started doing iOS it was something that I found very very handy it's a great learning tool it's important to understand that it's meant to save lightweight stuff like maybe a couple strings maybe a score in a game maybe like a true or false user setting if the user sets things like preferences the things that you can control in the app it's definitely not meant to save big chunks of user data for that we want to use something like core data realm sequel Lite so I can definitely do a video on each of those and I probably will to be honest and that's all I really had for you guys if you enjoy the video leave a like below subscribe if you're new I do iOS Swift objective-c videos pretty consistently yeah I'll see you in the next video thanks for watching