Well, it basically depends on several factors, including your background, level of experience, learning time, desired skill level, and learning route.
Level of Experience
Anyone can learn iOS development, but you will learn it more easily if you already have experience with programming. Of course, every programming language is different, but being able to code in other languages will help you learn iOS development much faster. For example, an experienced developer can learn Swift in a few days/weeks. But don't worry if you are a beginner! You can start from scratch and be a successful iOS developer.
Learning Time
The second biggest factor impacting how long it takes to learn iOS is the amount of time you're planning to spend learning.
If you have a full-time job, kids, or a busy life in general, and are not able to study more than 30 minutes per day, you might reach your goal in a year or two (and that's ok). You'll learn more quickly if you spend more time per day studying iOS development. In a few months, you will likely be able to develop a simple app.
Learning Route
How are you planning on learning? There are various ways to learn programming, such as a university degree and online courses.
If you are considering going to university, a degree in Computer Science might be a good option for you. On the other hand, studying at university is a long and expensive way of learning. The good news is you can become an iOS developer without a university degree. Luckily, there are a variety of platforms (such as LinkedIn Learning or Udemy) that offer affordable courses for various levels.
Simply put, you can learn coding faster or slower depending on your pace. Just keep in mind that learning iOS is not an easy task. It requires a lot of hard work and dedication. If you are serious about learning programming, you should stick to learning and coding every single day. Also, remember that as a developer you will never stop learning.
Here are 7 Steps to Become a Professional iOS Developer
Step 1: Get a Mac & Download Xcode
Step 2: Understand the basics of Xcode
Step 3: Learn the basics of programming with Swift
Step 4: Build apps with tutorials
Step 5: Deepen your knowledge about the iOS SDK and frameworks
Step 6: Deepen your Swift knowledge
Step 7: Develop your own app
Good luck!