1 00:00:08,190 --> 00:00:14,130 Hey everybody this is Caleb with Loeb's dot com and in this fantastic video we're going to write a function 2 00:00:14,220 --> 00:00:17,990 to remove objects from our core data persistent store. 3 00:00:18,000 --> 00:00:19,270 We're going to remove them forever. 4 00:00:19,280 --> 00:00:20,390 Going to get rid of them. 5 00:00:20,670 --> 00:00:25,410 And we're also going to add the ability to delete them from our table cell. 6 00:00:25,410 --> 00:00:27,610 We're going to be able to swipe tap delete. 7 00:00:27,630 --> 00:00:32,400 And we're going to be able to remove it and obliterate it forever as well as reload our table view and 8 00:00:32,400 --> 00:00:34,710 show all of the changes right away. 9 00:00:34,710 --> 00:00:35,630 It's so cool. 10 00:00:35,640 --> 00:00:41,430 So let's begin by pulling open that X code project and going into goals. 11 00:00:41,450 --> 00:00:48,660 VC OK now we're going to go down to our extension and we're going to write a function to remove objects 12 00:00:48,660 --> 00:00:51,440 from a managed context OK. 13 00:00:51,720 --> 00:00:59,490 Now to do this go ahead and type phunk remove let's do remove goal K and we're going to remove a goal 14 00:00:59,490 --> 00:01:01,140 at a certain index path right. 15 00:01:01,140 --> 00:01:07,320 We want to pull it out from our array of managed objects so we're going to go ahead and say at index 16 00:01:07,710 --> 00:01:14,370 path and we're going to pass an internal parameter here of index path which is a type index path lots 17 00:01:14,370 --> 00:01:15,510 of index path there. 18 00:01:15,750 --> 00:01:19,250 And we're going to go ahead and use that to remove our object. 19 00:01:20,190 --> 00:01:24,000 Now we need to get another managed context here. 20 00:01:24,000 --> 00:01:26,810 So we're going to create a reference to the managed context. 21 00:01:27,000 --> 00:01:28,220 So let's do that by typing. 22 00:01:28,230 --> 00:01:36,420 Guard let managed context equals app delegate persistent container view context and if we don't have 23 00:01:36,420 --> 00:01:38,840 that we're going to just return it just like below. 24 00:01:39,120 --> 00:01:43,220 We need just the reference to our managed context inside this function. 25 00:01:43,230 --> 00:01:47,000 Next what we're going to do is we're going to call managed context. 26 00:01:47,010 --> 00:01:47,690 Delete. 27 00:01:47,900 --> 00:01:48,560 OK. 28 00:01:48,930 --> 00:01:51,530 Now we need to delete a certain object. 29 00:01:51,540 --> 00:01:59,250 And as you know this array of goals is of type goal which if you go to the declaration of goal let's 30 00:01:59,250 --> 00:02:00,120 go find it. 31 00:02:00,150 --> 00:02:04,160 We can see that it inherits from an S. managed object from core data. 32 00:02:04,260 --> 00:02:10,890 So if we go back down we need to get a certain N-S managed object and to do that we're going to go into 33 00:02:10,890 --> 00:02:17,670 the goals array and we're going to pull out the item at the index path dot row we ask OK we're going 34 00:02:17,670 --> 00:02:23,400 to call this from our table view when we tap on a certain cell we're going to pass the index view of 35 00:02:23,400 --> 00:02:27,730 that cell which is going to correspond exactly with the goal from the goals. 36 00:02:27,780 --> 00:02:30,300 Because that's how the data is shown in the table view right. 37 00:02:30,420 --> 00:02:33,120 And then we're going to call managed context not delete. 38 00:02:33,120 --> 00:02:37,330 That's a function that's going to delete the goal at that and X path. 39 00:02:37,330 --> 00:02:37,900 OK. 40 00:02:38,190 --> 00:02:41,790 Now that is not enough though to actually delete what we need. 41 00:02:41,790 --> 00:02:44,970 We need to call managed contexts save. 42 00:02:44,970 --> 00:02:50,570 Do you remember in set when we save the function save we needed to settle this data. 43 00:02:50,580 --> 00:02:55,510 But then in order for it to actually pass in we need to call save on the managed context. 44 00:02:55,620 --> 00:03:00,750 We're going to do the same thing in remove We need to tell it we need to tell the manager context that 45 00:03:00,750 --> 00:03:01,960 it needs to update itself. 46 00:03:01,980 --> 00:03:09,490 So we're going to use a do and catch block in order to do this like you may have been expecting. 47 00:03:09,900 --> 00:03:16,830 And all we're going to do is just say Try managed context save you probably noticed that said you probably 48 00:03:16,830 --> 00:03:18,230 noticed that it said throws. 49 00:03:18,270 --> 00:03:20,570 And so we're going to go ahead and Debug. 50 00:03:20,570 --> 00:03:27,240 Print and we're going to say could not remove because that's what we're doing here and we're going to 51 00:03:27,240 --> 00:03:33,860 take the error from the dot save function and we're going to call error that localize description that 52 00:03:33,870 --> 00:03:35,400 will give us a little bit more information. 53 00:03:35,430 --> 00:03:36,870 If there's a problem. 54 00:03:36,870 --> 00:03:43,950 So let's say that we do successfully remove an object we're going to go ahead and just print successfully 55 00:03:44,520 --> 00:03:50,390 removed goal all right it looks good. 56 00:03:50,390 --> 00:03:55,760 So you know what guys this is all we need to do to remove something we need to find the item at the 57 00:03:55,760 --> 00:03:57,730 certain index path we want to remove. 58 00:03:57,800 --> 00:04:02,540 We're going to remove it from our managed context and we're going to save that managed context to update 59 00:04:02,540 --> 00:04:03,560 everything. 60 00:04:03,560 --> 00:04:05,350 That's all we've got to do to remove a goal. 61 00:04:05,360 --> 00:04:06,860 It's that easy. 62 00:04:06,860 --> 00:04:12,380 Next we need to enable our table view to be able to swipe and edit cells. 63 00:04:12,380 --> 00:04:16,440 So there are a couple of different table view delegate methods we need to call. 64 00:04:16,580 --> 00:04:20,310 We need to set a property called can edit row an index path. 65 00:04:20,390 --> 00:04:24,230 So go ahead and call that can edit row at index path. 66 00:04:24,230 --> 00:04:27,860 Believe it or not all we need to do to enable editing is call. 67 00:04:28,070 --> 00:04:29,860 Or is return true. 68 00:04:30,230 --> 00:04:31,540 Now we can edit our table view. 69 00:04:31,550 --> 00:04:33,010 It's that easy. 70 00:04:33,020 --> 00:04:36,830 Next what we're going to do is we're going to go ahead and set the editing style. 71 00:04:36,830 --> 00:04:43,760 So we're going to go ahead and call editing style Foro an index path and we're going to return a table 72 00:04:43,760 --> 00:04:45,850 view editing style. 73 00:04:46,070 --> 00:04:50,870 And if you push if you put a period you can see there are a few different things. 74 00:04:50,870 --> 00:04:54,370 There is insert delete and there is none. 75 00:04:54,380 --> 00:04:58,580 Now insert is going to add a plus a green circle enclosing with a little plus sign. 76 00:04:58,640 --> 00:05:00,800 Delete makes a red circle with a dash. 77 00:05:00,800 --> 00:05:04,970 We don't want either of those to show up on our cells because we have kind of a custom configuration 78 00:05:04,970 --> 00:05:05,480 here. 79 00:05:05,660 --> 00:05:07,340 So we're going to just press none. 80 00:05:07,430 --> 00:05:09,530 That way it doesn't show up anything special. 81 00:05:09,530 --> 00:05:13,140 And so we can actually get rid of the table view cell editing style thing. 82 00:05:13,400 --> 00:05:16,260 So our style has been saved. 83 00:05:16,280 --> 00:05:20,740 Now we need to actually create the editing actions so we can edit it. 84 00:05:20,750 --> 00:05:27,440 Now let's create the actions so let's go ahead and type edit actions forro at index path. 85 00:05:27,440 --> 00:05:28,440 Very very cool. 86 00:05:28,460 --> 00:05:30,530 So we're going to create two actions. 87 00:05:30,530 --> 00:05:36,840 One is going to delete and one is going to add progress in this video we're only focusing on deleting. 88 00:05:36,860 --> 00:05:39,890 So let's go ahead and create our delete action. 89 00:05:39,890 --> 00:05:41,420 Go ahead and type let delete. 90 00:05:41,450 --> 00:05:44,050 Action equals UI. 91 00:05:44,060 --> 00:05:47,340 Table View row action. 92 00:05:47,360 --> 00:05:48,950 Whoops row action. 93 00:05:49,100 --> 00:05:54,680 And what we're going to do is put a parentheses there so that we can instantiate it properly first with 94 00:05:54,680 --> 00:05:56,910 a style then with a title and last. 95 00:05:56,910 --> 00:06:00,620 There's a handler at the end where we actually set what the action does. 96 00:06:00,620 --> 00:06:07,460 So we're going to set the style to be destructive because destructive is what you use when data is going 97 00:06:07,460 --> 00:06:08,560 to be destroyed. 98 00:06:08,750 --> 00:06:11,490 The title is going to say delete. 99 00:06:11,960 --> 00:06:14,860 OK we're going to use all caps just so it looks extra cool. 100 00:06:14,930 --> 00:06:18,130 Deleting should be a very final thing. 101 00:06:18,380 --> 00:06:20,740 And press enter on the handler. 102 00:06:20,900 --> 00:06:26,990 And I want you to notice it's going to be returning a table view row action and an index path to us. 103 00:06:27,080 --> 00:06:27,710 OK. 104 00:06:27,710 --> 00:06:29,530 We're going to need the index path. 105 00:06:29,530 --> 00:06:31,940 We won't need the row action but we still need to give it a name. 106 00:06:31,940 --> 00:06:38,980 So go ahead and call RHO action WIPs action and the index path just type index path. 107 00:06:38,990 --> 00:06:43,090 So this is where we're going to actually do the stuff when we push the delete button. 108 00:06:43,250 --> 00:06:51,440 So in order to actually remove something we need to call self remove goal that function we just wrote 109 00:06:51,850 --> 00:06:54,530 Where are we going to get the index path from here. 110 00:06:54,530 --> 00:06:57,020 It's returned to us super easy. 111 00:06:57,020 --> 00:07:01,600 So go ahead and type index path and we have now remove that goal and saved it. 112 00:07:01,850 --> 00:07:08,150 Next what we need to do is we need to fetch all the data from our core data model because we've just 113 00:07:08,150 --> 00:07:08,840 removed it. 114 00:07:08,840 --> 00:07:09,650 It's changed. 115 00:07:09,650 --> 00:07:12,380 Now we need to fetch it all and we need to update our table view. 116 00:07:12,380 --> 00:07:15,620 So go ahead and call self fetch. 117 00:07:15,710 --> 00:07:19,130 But you know what we don't want to go through all of this completion junk again. 118 00:07:19,130 --> 00:07:23,530 So let's go ahead and let's find where we called it earlier here. 119 00:07:23,540 --> 00:07:27,950 And we're going to actually put this into its own function so we can call it from anywhere in this in 120 00:07:27,950 --> 00:07:28,580 this class. 121 00:07:28,580 --> 00:07:34,070 So cut this and below we're going to call phunk fetch. 122 00:07:34,190 --> 00:07:45,470 Fetch core data objects and pass that in there so we can now call fecche core data objects and that 123 00:07:45,470 --> 00:07:49,400 will do the same thing that we need to as when we want to call it here. 124 00:07:49,400 --> 00:07:55,730 So instead of calling the function from our extension we can call fetch core data objects and it does 125 00:07:55,730 --> 00:07:56,690 the same exact thing. 126 00:07:56,690 --> 00:07:59,740 We don't have to call on this big block of code. 127 00:07:59,750 --> 00:08:01,440 This one here we don't have to call it twice. 128 00:08:01,460 --> 00:08:05,090 We can just call it once with that function or we can call the same name twice. 129 00:08:05,090 --> 00:08:06,200 We can write less code. 130 00:08:06,380 --> 00:08:12,380 So now that we fetched all of the objects all the data is update and we can go ahead and call table 131 00:08:12,380 --> 00:08:16,550 view delete rows at index path. 132 00:08:16,550 --> 00:08:21,450 And what this is going to do is it's going to remove a certain row that we have deleted and then animate 133 00:08:21,500 --> 00:08:23,200 closing it's really cool. 134 00:08:23,240 --> 00:08:26,510 So it's asking for an array of index path. 135 00:08:26,690 --> 00:08:30,820 So we're going to give it that an array of index path from the returned index path. 136 00:08:30,950 --> 00:08:32,810 We're going to go ahead and give it an animation. 137 00:08:32,810 --> 00:08:33,400 And you know what. 138 00:08:33,410 --> 00:08:36,560 There are quite a few of them but we're just going to use Automattic. 139 00:08:36,700 --> 00:08:42,360 OK that's just a nice little fade up it pulls all the ones below it up and kind of animates it down. 140 00:08:42,410 --> 00:08:43,700 Very cool. 141 00:08:43,700 --> 00:08:48,390 So that is our daily action that's what we want to happen when we push delete. 142 00:08:48,390 --> 00:08:54,270 But we have not yet returned it to our table view yet we just have created it. 143 00:08:54,540 --> 00:08:58,890 But first before we do that we need to set a background color because you can set the color of these 144 00:08:58,890 --> 00:09:00,720 buttons to be whatever you want. 145 00:09:00,750 --> 00:09:03,380 But I found that it's easy if you just type delete action. 146 00:09:03,390 --> 00:09:06,890 Whoops delete action. 147 00:09:07,260 --> 00:09:08,340 Background color. 148 00:09:08,610 --> 00:09:13,350 And we're just going to use a color literal so tap on the color little double click it and we're going 149 00:09:13,350 --> 00:09:15,390 to set it to be a nice red color. 150 00:09:15,390 --> 00:09:17,190 Let's go ahead and let's do. 151 00:09:17,190 --> 00:09:17,890 Ooh yeah. 152 00:09:18,000 --> 00:09:19,110 You know that's nice. 153 00:09:19,110 --> 00:09:20,180 So select mirror Shino. 154 00:09:20,190 --> 00:09:22,020 That just means red I think. 155 00:09:22,170 --> 00:09:28,710 And now that we have set the background color we can properly return our delete action. 156 00:09:28,860 --> 00:09:32,880 OK but if I do that watch what happens it yells at me it's expecting an array. 157 00:09:32,880 --> 00:09:37,260 So even though there's only one we need to put it inside of an array we're going to add a second one 158 00:09:37,260 --> 00:09:38,410 later so it's OK. 159 00:09:38,700 --> 00:09:42,410 So go ahead and build and run this well for now I'm just building it. 160 00:09:42,640 --> 00:09:44,530 But now build and run. 161 00:09:44,550 --> 00:09:50,340 And let's go check it out in our applet see if we can properly delete an item from Chordata calling 162 00:09:50,340 --> 00:09:56,070 move goal removing the item at the index path fetching all of the objects after the data is changed 163 00:09:56,100 --> 00:09:57,510 and reloading the rows. 164 00:09:57,720 --> 00:10:01,530 So if we swipe we should be able to see our delete button. 165 00:10:01,530 --> 00:10:02,750 Very cool. 166 00:10:02,820 --> 00:10:04,470 Let's try to delete this one if I press it. 167 00:10:04,470 --> 00:10:06,160 Watch what happens. 168 00:10:06,360 --> 00:10:11,040 It deletes and I don't know if you saw that but it said successfully fetch data successfully removed 169 00:10:11,040 --> 00:10:12,420 goal successfully fetched data. 170 00:10:12,420 --> 00:10:17,730 So this is the initial loading that's when I removed the goal then it fetched the new data and deleted 171 00:10:17,730 --> 00:10:19,510 the row it showed the animation. 172 00:10:19,540 --> 00:10:24,090 Now you don't only have to swipe and press the button you can actually swipe all the way through and 173 00:10:24,090 --> 00:10:24,720 it will delete it. 174 00:10:24,720 --> 00:10:30,300 It's so cool that's just kind of an added thing that's in there for us so we can now successfully remove 175 00:10:30,300 --> 00:10:36,050 any goals that we want and show our table view when it's done because remember we have conditional code. 176 00:10:36,060 --> 00:10:42,960 If it's less then or if it's less than 1 if it's 0 it's going to hide our table just like that. 177 00:10:43,110 --> 00:10:44,550 Super super cool guys. 178 00:10:44,550 --> 00:10:45,720 This is amazing. 179 00:10:45,750 --> 00:10:51,560 The only thing that we need to do next is to add a new action here for adding progress. 180 00:10:51,750 --> 00:10:58,260 And at the very end when we meet our progress goal we need to set a UI view to fade in saying goal complete 181 00:10:58,680 --> 00:11:03,240 We're going to do that in the next video and we will call this app finished amazing work. 182 00:11:03,240 --> 00:11:06,310 Let's move on to that last video and let's get it started.