1.
Objective C
Part 1 Language

2.
Overview
NeXTSTEP
Smalltalk
https://www.youtube.com/watch?v=j02b8Fuz73A

3.
Language Design
Static and Strongly Typed
Keyword
No GC (ARC)
Superset of C (works as C compiler)
Not method but message
Protocol & Delegate Category

4.
Hello World
NSLog(@“Hello World”);
Interpolation %@

5.
Types
C types
int, char, float, const, unsigned
Objective C
NSObject, NSString, NSNumber, NSArray, NSDictionary
NSMutableArray
id

6.
Methods [Messages]
obj.method(param);
[obj message:param];
[obj sayHello:@“Hello!”];

7.
Methods [Messages]
obj.method(param1, param2);
[obj message:param1, keyword2:param2]
[person setFirst:@“John” setLast:@“Doe” setAge:@34]
The message signature is setFirst:setLast:setAge:

8.
- (void) sayHello: (NSString *) param {
NSLog(@“Hello %@ World”, param);
};
- (String) sayHello:(Type)param1
keyword2:(Type)param2
keyword3:(Type)param3 {};
Methods [Messages]
@Implementation

9.
List and Dictionary
NSArray *list = @[obj1, obj2, obj3, …];
NSDictionary *dict = @{ key:val, key:val}NSDictionary *dict = @{ key:val, key:val}

10.
^Callback (Block)
^ refers to an anonymous function
Define a block called Callback,
which takes a NSString,
then return void
Pass in a block
Implement a method called
ajax:word:
ajax takes a Callback type

11.
Class
Person.h
Person.m
Caller.m
#import “Person.h”
Person *p = [Person new];
@interface
@end
@implementation
@end
- (void) sayHello {…};
- (void) sayHello;
[p sayHello];
visible
implement

12.
Class
Person.h
Person.m
Caller.m

13.
Selector
Reflection in Java
SEL method = NSSelectorFromString(@“getFullname”);
[obj performSelector:method];

14.
<Protocol>
Interface in Java
C21Protocol.h

15.
Delegate Pattern
Like Java, Protocol is used in Delegate Pattern. But, use of Block is recommended.
-doYouKnowObjectiveC
<Protocol>
Developer.m
Manager.mClient
Delegate patterns are used in Views and
Controllers. I’ll show you the code in the
GUI part.
- delegate
-doYouKnowObjectiveC

16.
Category
Extends the existing class (like Ruby’s monkey patch)
Person+age.h
Person+age.m
Caller.m
To extend Person, prepare two files called:
Person+age.h
Person+age.m
Add getAge()

17.
Class Extension
Class extension is like anonymous Category ()
Define @interface in a .m file
The methods are private scope.
They are not visible from outside of the file.

18.
Property Option (avoid memory leak)
Button
View Controller
(weak) btnStrong
weak
View points to the Button object strongly,
while Controller.btn points to the Button weekly.
Thus, Compiler (ARC) can delete the Button object when the Strong link
is detached.
There is no GC in Objective-C. Compiler will insert destructor
statements.