Objective-C - Lesson 04

[judaco]

//
//  main.m
//  Lesson04
//
//  Created by hackeru on 22/03/2017.
//  Copyright © 2017 juda. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Square.h"
#import "XYPoint.h"

@interface ClassA : NSObject
{
    int x;
}

-(void) initX;

@end

@implementation ClassA

-(void)initX {
    x = 100;
}

@end

@interface ClassB : ClassA

-(void) printX;
-(void) printX: (int) c;
-(void) printX: (int) c and: (int) d;

@end

@implementation ClassB

-(void)printX {
    NSLog(@"x = %i", x);
}

-(void)printX:(int)c{
    NSLog(@"test1");
}

-(void)printX:(int)c and:(int)d {
    NSLog(@"test2");
}

-(void)initX {
    x = 200;
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
                ClassB *b = [[ClassB alloc] init];
                [b initX];
                [b printX];
                [b printX: 3];
                [b printX: 3 and:5];

                ClassA *a = [[ClassB alloc] init];
                [a initX];

        Rectangle *s1 = [[Square alloc] init];
        //BOOL respondsToSetSide = [s1 respondsToSelector: NSSelectorFromString(@"setSide:")];
        //if (respondsToSetSide) {
         //   [s1 setSide: 7];
            [s1 setWidth:7 andHeight:3];
            NSLog(@"area is %i", [s1 area]);
        //}

        XYPoint *o = [[XYPoint alloc] init];
        [s1 setOrigin: o];

        BOOL isKindOfRectangle = [s1 isKindOfClass:[Rectangle class]];
        BOOL isKindOfSquare = [s1 isKindOfClass:[Square class]];
        NSLog(@"%i %i", isKindOfRectangle, isKindOfSquare);

        if ([a class] == [b class]) {
            NSLog(@"a and b are the same class");
        }else{
            NSLog(@"a and b are NOT the same class");
        }

        @try {
             [b performSelector: NSSelectorFromString(@"printX")];
        } @catch (NSException *exception) {
            NSLog(@"haval %@", [exception description]);//example with String, if the method in the memory is not appearing, then i'll get an error message of unrecognized method of my name "Juda", but when I put a "printX", then I\ll get the value of x in the memory.
        } @finally {
        }

        NSLog(@"done");
    }
    return 0;
}

[judaco]

Exceptions

//
//  main.m
//  Lesson04 - ErrorHandling
//
//  Created by hackeru on 22/03/2017.
//  Copyright © 2017 juda. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface MyException : NSException
@property int errorCode;

@end

@implementation MyException

@end

int divide (int x, int y);//the signature of the method, which is outbound of the Main - this is coming from #C lang.

int main(int argc, const char * argv[]) {
    @autoreleasepool {
//        NSArray *arr = [NSArray array];
//        @try {
//            @throw [[NSException alloc] initWithName:@"my name" reason:@"my reason" userInfo:nil];//initializer not default, because we have params,
//            id x = [arr objectAtIndex: 2];
//            NSLog(@"after the error");
//        } @catch (NSException *exception) {
//            NSLog(@"some error occured %@", exception.reason);//name gives NSRangeException, reson gives NSArray object index exception, index 2 beyond bounds for empty NSArray
//        } @finally {
//            
//        }

        @try {
            NSLog(@"done %i", divide(8, 0));
        } @catch (MyException *exception) {
            NSLog(@"some error ocurred - %@ - %@ - %i", exception.name, exception.reason, exception.errorCode);
        } @catch (NSException *exception){
            NSLog(@"regular exception");
        } @finally {

        }
        NSLog(@"done");
    }
    return 0;
}

int divide (int x, int y) {
    if (y == 0){
        MyException * e = [[MyException alloc] initWithName:@"arithmethic exception" reason:@"division by zero" userInfo:nil];
        e.errorCode = 404;
        //@throw e;
        @throw [[NSException alloc] initWithName:@"regular ex" reason:@"no real reason" userInfo:nil];
    }
        return x/y;
}

[judaco]

//
//  main.m
//  Lesson04 - Initializers
//
//  Created by hackeru on 22/03/2017.
//  Copyright © 2017 juda. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Dog : NSObject
-(void) bark;
-(void) goToSleep;
-(void) setName: (NSString *) n;
-(NSString *) getName;
@end

@implementation Dog
{
    NSString *name;
    int age;
}
//go look at the Dog = (Dog *) - this is an override
-(instancetype)init{
    self = [super init];
    if (self) {//like boolean, if self is not nil (=0)
        name = @"snoopy";
        age = 0;
    }
    return self;
}
-(instancetype)initWithName: (NSString *) n{
    self = [super init];
    if (self) {//like boolean, if self is not nil (=0)
        name = @"snoopy";
        age = 0;
    }
    return self;
}
-(void)bark {
    NSLog(@"Waf waf");
}
-(void)goToSleep {
    NSLog(@"Zzzzzz");
}
-(void)setName:(NSString *)n {
    name = n;
}
-(NSString *)getName {
    return name;
}

@end

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Dog *d = [Dog alloc];//alloc is static - give us a place in the memory (allocate us a place)
        d = [d init];//init is not static, init sets on an object from specific type (here dog)
        [d setName: @"peter"];
        [d init];
        NSLog(@"name: %@", [d getName ]);
    }
    return 0;
}