What will be printed out to the console when we run that code? We will get a is equal to b , as both objects a and b are pointing to the same object in memory.
Now we get a is NOT equal to b since these pointers are now pointing to different objects even though those objects have the same values. This problem can be avoided by relying on isEqual , or type specific functions. In our code example, we should replace line 3 with following code for it to always work properly:. What does represent? Why is it being used? It is probably not obvious that this corresponds to the number of seconds in 2 days there are 24 x 60 x 60, or 86,, seconds in a day.
Rather than using hard-coded values, you could define a value using the define statement. For example:. So, if you have define in a header file and import it somewhere, all occurrences of the defined value in that file will be replaced too. This works well, except for one issue. To illustrate the remaining problem, consider the following code:. What would you expect the value of y to be after this code executes? If you said 1. The answer is that define has no information about the type. So, in our case, we have a division of two Int values 3 and 2 , which results in an Int i.
Common Mistake No. 1: Not Understanding Asynchronous Processes
Using the default keyword in a switch statement can lead to bugs and unexpected behavior. Consider the following code in Objective-C:. This code works as intended, allowing only admin users to be able to change other records. If we forget to update this switch statement, the code will compile, but it will not work as expected. However, if the developer used enum values instead of the default keyword from the very beginning, the oversight will be identified at compile time, and could be fixed before going to test or production.
Here is a good way to handle this in Objective-C:. Many iOS developers use NSLog in their apps for logging, but most of the time this is a terrible mistake. If we check the Apple documentation for the NSLog function description , we will see it is very simple:. What could possibly go wrong with it? In fact, nothing. Better approach is to replace NSLogs with configurable CocoaLumberjack or some other logging framework. Apple makes a massive ongoing effort to introduce new hardware and features for iOS itself, while also continually expanding the Swift language.
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10 Best iOS 12 App Development Course  [UPDATED]
Performance Cookies. Targeting Cookies. Allow all Save. Build your own professional and modern iOS applications using Swift 4 Create various kinds of project, managing files, accessing Xcode's documentation systems, and using the LLDB debugger.
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Develop modern, stylish, and consumer-focused iOS applications from scratch, in real time. Use Apple Xcode, create projects, write code, and design user interfaces using Interface Builder Focus on the key components and patterns of native iOS development, giving you an excellent foundation to build upon. The Course Overview.
Getting Xcode. A Quick Tour of Xcode.
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Running the Template App. The Xcode Debugger and Breakpoints. Accessing Documentation in Xcode. Creating the Project.
Kotlin Playground: Edit, Run, Share Kotlin Code Online
Creating the Basic User Interface. Introduction to Swift Optionals. Coding the Web View Controller. Adding a Toolbar. Adding a Search Controller. Protocols and the Delegate Pattern. Wiring Up the Search Bar. Adding Share Functionality. Improving the Search Bar and Controller Configurations.
Improving the Toolbar Layout.
Real World Example: Creating a Journal Entry App with Core Data in Swift Part 1.
Enabling and Disabling the Back and Forward Buttons. Adding a Simple Loading Indicator. Intro and Creating the Project. Creating the Note Model Interface. Implementing the Note Model. Auto-Generating the Note Title. Creating the Data Source Interface. Implementing the Outline Data Source. Swift Error Handling.