Beginer Objective-c keys

key gợi nhớ mã lệnh trong objective-c ( phục vụ mục đích cá nhân 😀 )

Macros: lệnh đơn độc

#import <Foundation/Foundation.h>

#define PI 3.14159

#define RAD_TO_DEG(radians) (radians * (180.0 / PI))

Typedef: tạo 1 cấu trúc mới hoặc tái tạo cấu trúc cũ

typedef unsigned char ColorComponent;

ColorComponent red = 255;

NSLog(@” %hhu”,red);


typedef struct {

unsigned char red;

unsigned char green;

unsigned char blue;

} Color;

Color carColor = {255, 160, 0};

NSLog(@”Your paint job is (R: %hhu, G: %hhu, B: %hhu)”,,,;



} CarModel;


Primitive Array: array gốc của C, cao hơn là NSArray, NSMutableArray

int years[4] = {1968, 1970, 1989, 1999};

years[0] = 1967;

for (int i=0; i<4; i++) {

NSLog(@”The year at index %d is: %d”, i, years[i]);


Pointers: & trả về memory address, * trả về nội dung,có thể gián =NULL

int year = 1967;       // Define a normal variable

int *pointer;   // Declare a pointer that points to an int

pointer = &year;// Find the memory address of the variable

NSLog(@”%d”, *pointer);//get its value from the address


char model[5] = {‘H’, ‘o’, ‘n’, ‘d’, ‘a’};

char *modelPointer = &model[0];

for (int i=0; i<5; i++) {

NSLog(@”Value at memory address %p is %c”,

modelPointer, *modelPointer);



NSLog(@”The first letter is %c”, *(modelPointer – 5));


Pointers in Object-C

NSString *anObject;    // An Objective-C object

anObject = NULL;       // This will work

anObject = nil;        // But this is preferred

int *aPointer;         // A plain old C pointer

aPointer = nil;        // Don’t do this

aPointer = NULL;       // Do this instead


Run C, C++ in Objective-C: đổi đuôi file thành *.mm



arc4random_uniform((maximum – minimum) + 1) + minimum;

trả về giá trị giứa 0 và 1 số bất kì

Close Keyboard: add Tap Gesture Reconizer -> Layout ->add event cho Tap…

[<ten textbox> resignFirstResponder];

Currency to number

-(void) currencyToDouble: (NSString*) currency{

NSNumberFormatter *numberFormatter = [[ NSNumberFormatter alloc] init];

[numberFormatter setNumberStyle: NSNumberFormatterCurrencyStyle ];


NSNumber *number = [numberFormatter numberFromString:currency];

NSLog(@”%@ convert to number is: %@”,currency,number);



NSDate to part:

-(void) datePart:(NSString *)dateString withFormat:(NSString *)format toGetPart:(NSString*) typeOfDate{

NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];

[dateFormat setDateFormat:format];

NSDate *date = [dateFormat dateFromString:dateString];

NSCalendar *calendar = [NSCalendar currentCalendar];

NSDateComponents* components = [calendar components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay fromDate:date];

if([[typeOfDate lowercaseString] isEqualToString:@”day”])

NSLog(@”Day is:%d”, (int)[components day]);

if([[typeOfDate lowercaseString] isEqualToString:@”month”])

NSLog(@”Month is: %d”, (int)[components month]);

if([[typeOfDate lowercaseString] isEqualToString:@”year”])

NSLog(@”Year is: %d”,(int)[components year]);



NSMutableArray *oldSkoolFiltered = [[NSMutableArray alloc] init];

for (Book *book in bookshelf) {

if ([book.publisher isEqualToString:@”Apress”]) {}



NSPredicate *predicate =[ NSPredicate predicateWithFormat:@”publisher == %@”, @”Apress” ];

NSArray *filtered= [ bookshelf filteredArrayUsingPredicate:predicate];


//Regular Expressions

[NSPredicate predicateWithFormat:@”title MATCHES ‘.*(iPhone|iPad).*'”]; // iphone or ipad in title



NSArray *favoritePublishers = [NSArray arrayWithObjects:@”Apress”, @”O’Reilly”, nil];

predicate = [NSPredicate predicateWithFormat:@”publisher IN %@”, favoritePublishers];

//using KVC compliant

predicate=[NSPredicate predicateWithFormat: @”authors.lastName CONTAINS[cd] %@” , @”Mark” ];



@protocol PrintProtocolDelegate

– (void)processCompleted;


@interface PrintClass :NSObject

{    id delegate; }

– (void) printDetails;

– (void) setDelegate:(id)newDelegate;


@implementation PrintClass

– (void)printDetails{

NSLog(@”Printing Details”);

[delegate processCompleted];


– (void) setDelegate:(id)newDelegate{

delegate = newDelegate;



@interface SampleClass:NSObject<PrintProtocolDelegate>

– (void)startAction;


@implementation SampleClass

– (void)startAction{

PrintClass *printClass = [[PrintClass alloc]init];

[printClass setDelegate:self];

[printClass printDetails];




NSLog(@”Printing Process Completed”);



int main(int argc, const char * argv[]){

NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

SampleClass *sampleClass = [[SampleClass alloc]init];

[sampleClass startAction];

[pool drain];

return 0;



UI Switch

On/off : <ten switch>.isOn

[<ten switch> setOn:<BOOL> animated:YES];

UI Segmented Controll: index of which clicked

[sender selectedSegmentIndex]==0

Fix Table Line:

if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {

[self.tableView setSeparatorInset:UIEdgeInsetsZero];


Send Notification between View

receive class

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataReceived:) name:@”addData” object:nil];

-(void)dataReceived:(NSNotification *)noti


NSDictionary *dataController = noti.object;

BirdSighting *bird = [dataController objectForKey:@”BirdSighting”];

[self.dataController addBirdSightingWithSighting:bird];

NSLog(@”dataReceived :%@”, noti.object);


sender class >

[[NSNotificationCenter defaultCenter] postNotificationName:@”addData” object:[NSDictionary dictionaryWithObject:bird forKey:@”BirdSighting”]];


Change style of Tab Bar


[[UITabBarItem appearance] setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:
[UIColor whiteColor], NSForegroundColorAttributeName,
nil] forState:UIControlStateNormal];
UIColor *titleHighlightedColor = [UIColor colorWithRed:153/255.0 green:192/255.0 blue:48/255.0 alpha:1.0];
[[UITabBarItem appearance] setTitleTextAttributes:[NSDictionary dictionaryWithObjectsAndKeys:
titleHighlightedColor, NSForegroundColorAttributeName,
nil] forState:UIControlStateHighlighted];


Get Cell of Table View


NSArray *cells = [tableView visibleCells];

NSMutableArray *cells = [[NSMutableArray alloc] init];

for (NSInteger j = 0; j < [tableView numberOfSections]; ++j)


    for (NSInteger i = 0; i < [tableView numberOfRowsInSection:j]; ++i)


        [cells addObject:[tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:i inSection:j]]];



for (CustomTableViewCell *cell in cells)


    UITextField *textField = [cell textField];

    NSLog(@”%@”; [textField text]);


Add Navigation Button Item

UIBarButtonItem *leftBarButtonEdit =  [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@”Checked”] style:UIBarButtonItemStylePlain target:self action:@selector(btnEditField:)];

    UIBarButtonItem *leftBarButtonDelete =  [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@”Delete”] style:UIBarButtonItemStylePlain target:self action:@selector(btnDeleteField:)];


    [self.navigationItem setRightBarButtonItems:@[leftBarButtonEdit,leftBarButtonDelete] animated:YES];

Change Status Bar Color

Open the info.plist file of your app and set the UIViewControllerBasedStatusBarAppearance to NO

[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

Switch View Controller with animation

-(void)switchViewController:(NSString *)storyboardID{

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@”Main” bundle:nil];

    UIViewController *visibleViewController = [storyboard instantiateViewControllerWithIdentifier:storyboardID];

//    [UIView transitionWithView:self.window

//                      duration:0.5

//                       options:UIViewAnimationOptionTransitionCurlUp

//                    animations:^{ self.window.rootViewController = visibleViewController; }

//                    completion:nil];

    CATransition *transition = [CATransition animation];

    transition.duration = 0.5;

    transition.type = kCATransitionPush;

    transition.subtype = kCATransitionFromRight;

    [transition setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];

    [self.window.layer addAnimation:transition forKey:nil];


    self.window.rootViewController = visibleViewController;


Alert View with Indicator

UIAlertView * myAlertView = [[UIAlertView alloc] initWithTitle:@”Loading” message:@””



                                                 otherButtonTitles:nil, nil];


    UIActivityIndicatorView *loading = [[UIActivityIndicatorView alloc]

                                        initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray]; =;

    loading.hidesWhenStopped = true;

    loading.activityIndicatorViewStyle = UIActivityIndicatorViewStyleGray;


    [myAlertView setValue:loading forKey:@”accessoryView”];

    [loading startAnimating];

    [myAlertView show];



    int64_t delayInSeconds = 3; // Your Game Interval as mentioned above by you


    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);


    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){


        [myAlertView dismissWithClickedButtonIndex:0 animated:YES];

        [appDelegate switchViewController:@”SlideMenuView”];




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