Write Objective C code for absolute beginner (Quick Guide)

Objective C is basically object oriented C, its an extend C programming language. So, it has the basic syntax as C, are the primitive types, structures, functions, control flows (if, else, for, ...), pointers, and libraries.

What objective C adds to C ---> Defining new class, instance methods, methods invocations, automatic synthesizing of accessor methods, static and dynamic typing, blocks plus protocols and categories.

Lets start with classes and objects, a class encapsulates the data and defines actions to operate on that data and object is run time instance of the class.

Class extensions in objective C:

• .h is the header file.
• .m is the implementation file.
• .mm is the implementation file if you are using C++ in your code as well.

 .h file:

@interface className : parentClassName

{
    // Member variables

}

 //method declarations

@end





.m file: 

// #import directive is like #include directive in C the difference is that #import directive makes sure // that the same header file never included more than once.

#import className.h

@implementation className
{
   

}

Objective C allows both static and dynamic typing:

className *object1;  // Static typing

id       object2;  // Dynamic typing

NSString *myName;  // static typing

Methods in objective C ----> Instance Methods and Class Methods
For instance method you need to create an instance of the class first then use the method. But Class Method dose not requires an instance of the class to be receiver of the message.

Instance method declaration is preceded by a minus sign (-). For Class Methods, its a plus sign (+).
 
written by: infinitywebseo 

UIDocument does not allow you to write strings directly to disk

If you are using UIDocument in your app, always remember that UIDocument doesn't allow you to write strings directly to disk.

You need to package the string value in NSData then you can write it to disk. You can do it using the contentsForType:error method.

Below is a sample code, first check that the string is not NULL :

- (id)contentsForType:(NSString *)typeName error:(NSError **) myError{
    if (!self.stringDocument)
        self.stringDocument = @"";

    NSData *nsDataDocument = [self.stringDocument
                           dataUsingEncoding:NSUTF8StringEncoding];
    return nsDataDocument;
}

written by: infinitywebseo 

iOS 7 --> Things that you need to change about your app

 
All the contents on this blog are derived from apple developer website, its just a quick short-list for my own personal use.  I hope you find it useful.


Things I must do:

• Update app icon to 120 x 120 (iOS 7 - Higher Resolution).
• Update the launch image to include the status bar area.
• Support Retina display.

Things I should do:  

Prepare for borderless buttons by moving away from supplying button background images and by reassessing your layout.

Use translucent UI Element & Auto-layout.

View controllers should use full screen layout. Don't use "wantsFullScreenLayout", its deprecated in iOS 7. Instead use the following properties:

• edgeForExtendedLayout
• extendedLayoutIncludeOpaqueBars
• automaticalAdjustScrollViewInsets

For custom animated transitions between views click on --> UIViewControllerInteractiveTransitioning Protocol Reference. 


Using tint color: In iOS 7 tint is a property of UIView. Specify a tint color for entire app using following line: window.tintColor = [UIColor purpleColor]; By default tint color is nil which means that it uses the parent tint color. 
Remember, its best to change tint color when the app is off screen.


Bars and Bar Buttons barPosition in iOS 7 is a property for identifying bar position. The UIBarPositionTopAttached -----> a bar is at the top of the screen and its background extends upward into the status bar area. 
UIBarPositionTop ------> a bar is at the top of its local context—for example, at the top of a popover—and that it doesn’t provide a background for the status bar. 


Status Bar iOS 7
In iOS 7 You can control the style of the status bar from an individual view controller and change it while the app runs. In order to do it, add the UIViewControllerBasedStatusAppearance key to an app's Info.plist file and give it the value YES.


Navigation Bar iOS 7
Bar Style: by default the translucent property is YES.
Appearance: A one-pixel hairline appears a the button edge.  
Tinting: Use tintColor to tint bar button items.
             Use barTintColor to tint the bar background.


Collection View iOS 7
Collection view supports animated transitions between layouts. Click to read the documentation ------> UICollectionViewTransitionLayout Class Reference

Image View iOS 7
UI Image contains tintColor property and when image uses UIImageRenderingModeAlwaysTemplate mode, tintColor is applied to the image.

Map View iOS 7
In iOS 7 there is a new class called MKOverlayRenderer which you can use to create overlay on the top of map view.


Page View Controller iOS 7
To specify orientation use the following methods:

• pageViewControllerPreferredInterfaceOrientationForPresentation
• pageViewControllerSupportedInterfaceOrientations 

Scrol View in iOS 7  
automaticallyAdjustsScrollViewInsets ----> to manage scroll view insets.

written by: infinitywebseo 

 

 

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