iOS Development Learning Note 017-what is iOS development

Application development Process 1, questions to consider for iOS development

　　who is the user? the content and user experience of different applications varies greatly depending on what application you want to write, which may be a children's game, a to-do list application, or an application that tests its own learning results.

What is the purpose of the application? It is important to give the application a clear purpose. Understanding the motivations that inspire users to use applications is a starting point for defining purpose.

What problems does the application try to solve? an application should solve a single problem perfectly, rather than trying to solve a number of distinct problems. If you find that an application is trying to solve an unrelated problem, it is best to consider writing multiple applications.

what does the application render? consider the type of content the application will present to the user, and how the user interacts with the application, and then design a user interface that is commensurate with it.

When you first start developing your application, you don't have to define a perfect or complete application concept. However, once you have the concept, you will be aware of your development goals and implementation methods.

2. Design User Interface

The biggest challenge in building a user interface might be to turn concepts into design and implement the design. You can use a concatenation diagram to simplify this process. tandem Diagrams Use a graphical environment to design and implement the interface in one step. When building the interface, you can fully see the content of the build, immediately get feedback about whether the interface is working properly, and immediately make changes to the interface visually.

The design and debugging of the interface is mainly in the series diagram.

3. Define the interaction

Without logical support, the functionality of the user interface will be limited. Once the interface is created, you can define how users interact with what they see by writing code to respond to user actions in the interface.

It is important to understand that IOS applications are event-driven programming before considering adding behavior to the interface. In event-driven programming , the process of an application is determined by the event: a system event or user action. Actions performed by the user in the interface trigger events in the application. These events cause the application's logic to be executed and its data processed. The application's response to user actions is faithfully reflected in the interface.

Define how the user interacts with the interface from an event-driven programming perspective. Because it is the user, not the developer, that controls when to execute some part of the application's code. You want to confirm what actions the user can perform and how to respond to those actions.

4. Implementation behavior　

After you define the actions that users can perform in an application, you can write code to implement the behavior.

The objective-c programming language is used most of the time when writing code for IOS applications.

Objective-c originates from the C programming language, which provides object-oriented functionality and dynamic runtime. It contains all the elements you are familiar with, such as basic types ( int , float etc.), structures, functions, pointers, and process control structures (and while if...else for statements). You can also access standard C library routines, such as stdlib.h stdio.h those declared in and.

Other

There are three common types of events:

• Touch and drag events. Touch and drag events occur when the user interacts with the control by touching or dragging. Touch events are staged in several stages. For example, when a user touches a button for the first time, the touch down Inside event is triggered, and if the user's finger is dragged off the button, the corresponding drag event is triggered. Touch up Inside is sent when the user's finger is lifted off the button but still stays within the range of the button edge. The touch up Outside event is triggered if the user has pulled off the button (actually canceling the touch) before lifting his finger.

• Edit the event. the user edits the text field, and the edit event occurs.

• The value Change event. the control is manipulated by the user, causing the control to produce a series of different values, which occur as value change events.

Adaptive window

use Auto Layout to place text fields

1. In the Project Navigator, select Main.storyboard .

2. In the concatenation diagram, select the Text field.

3. On the canvas, Control-Drag from the text bar to the top of the scene until the text bar is surrounded by blank areas. This area is the parent view of the text column.

   When you stop a drag operation, a shortcut menu appears in its place.

4. Choose "Top Space to top Layout Guide" from the shortcut menu.

   A spacing constraint is created between the top of the text bar and the navigation bar.

   If other menus appear (such as the leading Space to Container menu item), you are not dragging vertically to the top of the screen. Xcode determines what type of constraint you intend to generate based on the direction you drag, and determines which objects the constraint is associated with based on the starting and ending points of the drag. You can continue to experiment with different drag orientations to see which constraints are available.

5. After you have tried, Control-drag from the text bar to the right to the parent view to create the Trailing Space to Container constraint.

6. Control-Drag from the text bar to the left to its parent view to create the leading Space to Container constraint.

Run to see the effect, rotate the screen, the text bar will automatically follow the method of narrowing.

iOS Development Learning Note 017-what is iOS development