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Guess what? Simply click on the Xcode Run button the first button at the top of the screen to compile and run your app in the simulator. At this stage, they should be self-explanatory.
Often just typos when declaring your variables. Remember, Xcode is case-sensitive. Right now your list of quotes are hard-coded into the app. A property list is a special XML format defined by Apple that are designed to store basic data types like strings, numbers, arrays, and dictionaries. They are very easy to create, and to read and write from code, so they are a great way to get in small bits of data into your app. Create a new file by right-clicking on your project root on the left sidebar the Project Navigator and selecting New File.
Select the location to save your new file usually somewhere within the project folder for the tutorial project and name the file quotes. You can either edit the property list file from within Xcode in a grid-view as a list of properties or as a text file. Since you want to quickly add all the quotes by copying and pasting, opening as source code probably would be the faster route.
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If you want though, you can try the grid view approach and try to figure out how to add the same values as below using that method. Now, add your movie quotes by copying and pasting the following into quotes in source code mode :. These are just a few quotes to serve as examples. Have some fun and add your own favorites. Now that you know how the different editing modes work, you can always switch back and forth as you like.
Property lists are cool, but can be very uncool when you get an error. Earlier versions of Xcode gave line numbers for errors. I think it was from version 4 onwards that this helpful feature was excluded. If you really get stuck, you need to methodically go through your file. I do this a bit too often to be frank to make it easier: copy my plist file, then remove chunks a bit at a time to identify the approximate location of the error. Having created your lovely property list, you are now ready to load it into an array for use.
To try out your new array, you might think that all you really need to do is change getting the random quote from your personal quotes array to the movie quotes array. So, in quoteButtonTapped: you simply replace all references to myQuotes with movieQuotes, right? But that alone will not work, as you will find if you try it. This is because myQuotes was an array of quote strings. But movieQuotes is not an array of strings. You can look up entries in a dictionary with the valueForKey method.
So replace quoteButtonTapped with the following code which switches over to using the movieQuotes array but also gets the quote by using the right key for each quote dictionary:.
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Keep the commented out line in section 3 as it will come in handy later. Build and run and enjoy your new movie quotes! Awesome, now you have a file that can read quotes from an external file! This can be especially handy if you want someone else to fill in some quotes for you as you continue to work on your app. First you need to go back to your class header file, ViewController. This achieves the effect of having three different quote types — or rather, the ability to select between one of the three. Having created your Segmented Control, you need to link it to the outlet in your class.
You can use the same method as before to hook up the control to the quoteOpt property on the View Controller. A predicate is a useful object that filters an array. I find them quite useful when I have a categorized property list.
It saves you from having to create separate property lists. Now the user will see myQuotes only when they select the third option. And as you might recall, since the segment control starts at index 0, index 2 means the third item. For the predicate fun, first you figure out the category you need based on the selected segment control and then use the category to create a filtered array of quotes that matches the category. Stay with me! Okay, build and run. Check that you see the right type of quote depending on your selection.
If you are always getting the same type, my guess would be that you may not have linked the Segmented Control to your class. If the quote has a source in the property list, then the app should display that as well. So add the following to quoteButtonTapped: after the first line in section 2. You get the source from the array and check that it contains a value by making sure that its length is not zero. Then you build a new display string by combining the quote and the source using stringWithFormat.
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If you want to check for a particular movie title or for that matter any other string attribute starts with a particular value, you can do that too. Say you want to display some extra text if the quote is from a Harry Potter movie — add the following right above section 2. As you can guess, hasPrefix is used to check if the start of the string has a particular text value. Build and run your app to make sure that it works as you expect it to. Pay attention to the different categories and to Harry Potter movie quotes to make sure that it all works correctly. This will illustrate how to loop through an array, which you might need to do if you want to iterate over each item in an array to process each item.
A for loop is used to loop through the array from row 0 to the last row. One last thing. So far, each has done the same job in this project. As the name implies, a mutable array can be changed whereas a normal NSArray is static and you cannot add new items to the array or delete items from the array easily.
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For example, if you wanted to update the array after a row had been selected in order to show that that quote had already been displayed, you would need an NSMutableArray. You're using a predicate , so you first need to find the row in movieQuotes and then update it. Add the following code after section 2. You loop through the array and check each row to see if it's the row you're looking for. Again you use isEqualToString ; this time, however, you're comparing two string variables.
To update the row in the array, you retrieve the object for the row in question and update the object. This is starting to get a bit advanced for this tutorial, but it's useful to know. Since you're updating the source string and since the source string is what is used to select quotes for each category, the row will not be included next time you use NSPredicate to filter the array. And that's quite neat. Here is a sample project with all of the code from the above tutorial.
Well, you've reached the end of this little project. The wapper also requires additional steps to set up. Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks. The following code samples show how to handle common tasks in Objective-C:. You can use them to find out the reason for errors. To find out how to identify and handle errors, see Handling errors. Table of contents.
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Xcode 10 or later. Once your Podfile is prepared, add the pod command below to your target: platform :ios , '