Astuces

              
// MySingletonObject.h
@interface MySingletonObject : NSObject
+ (id)sharedInstance;
@end

// MySingletonObject.m
#import "MySingletonObject.h"
@implementation MySingletonObject
+ (id)sharedInstance {
    static MySingletonObject *__sharedInstance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        __sharedInstance = [[MySingletonObject alloc] init];
    });
    return __sharedInstance;
}
@end

            

              
void SwizzleInstanceMethod(Class c, SEL orig, SEL new);
void SwizzleClassMethod(Class c, SEL orig, SEL new);

#import <objc/runtime.h>

void SwizzleInstanceMethod(Class c, SEL orig, SEL new)
{
    Method origMethod = class_getInstanceMethod(c, orig);
    Method newMethod = class_getInstanceMethod(c, new);
    if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    else
        method_exchangeImplementations(origMethod, newMethod);
}

void SwizzleClassMethod(Class c, SEL orig, SEL new) 
{
    Method origMethod = class_getClassMethod(c, orig);
    Method newMethod = class_getClassMethod(c, new);
    c = object_getClass((id)c);
    if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    else
        method_exchangeImplementations(origMethod, newMethod);
}

// Example: 
@implementation NSParagraphStyle (JTParagraphStyleDebug)

+ (void)load {
    SwizzleInstanceMethod([self class], @selector(initWithCoder:), @selector(initWithCoderSwizzled:));
}

// -[NSParagraphStyle initWithCoder:] is called when an NSAttributedString is specified in an UILabel in Interface Builder.
- (id)initWithCoderSwizzled:(NSCoder *)aDecoder {
    self = [self initWithCoderSwizzled:(id)[[UINibDecoderProxy alloc] initWithTarget:aDecoder]];
    return self;
}

@end

            

              
// appliquer le masque dans un thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        UIImage* image = [UIImage imageFromStringURL:@"myImage.jpeg" useCache:YES];
        UIImage* mask = [UIImage imageNamed:@"circlemask.jpeg"];
        image = [self maskImage:image withMask:mask];
        dispatchasync(dispatch_get_main_queue(), ^{
            [imageView setImage:image];
        });
    });

//methode pour masquer l'image
- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
    CGImageRef maskRef = maskImage.CGImage; 
    CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
        CGImageGetHeight(maskRef),
        CGImageGetBitsPerComponent(maskRef),
        CGImageGetBitsPerPixel(maskRef),
        CGImageGetBytesPerRow(maskRef),
        CGImageGetDataProvider(maskRef), NULL, false);
\
    CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);
    return [UIImage imageWithCGImage:masked];
}

            

              
-fno-objc-arc //no arc
-fobjc-arc //with arc

            

              
//array
NSArray* myArray = @[@"un",@"deux",@"trois"];
NSString* two = myArray[1];
//
//Dictionary
NSDictionary dic = @{ @"one" : @1,
                           @"two" : @2,
                           @"three" : @3 };
NSNumber* two = dic[@"two"];
//subscripting / indexing  (peut importe le type de l'objet retourné) Merci @_jonasf_
id item1 = myArray[1];
id item2 = dic[@"myKey"];
dic[@"myKey"] = newObject;

//NSNumber
NSNumber* booleanNumber = @YES;
NSNumber* expression = @(255.f - 43.f)
//
//NSString
char* str = "My C-like string";
NSString* objCString = @(str);

            

              
#define RADIANSTODEGREES(radians) ((radians) * (180.0 / MPI))
#define DEGREESTORADIANS(angle) ((angle) / 180.0 * MPI)

NSLog(@"Output radians as degrees: %f", RADIANSTODEGREES(0.785398));
NSLog(@"Output degrees as radians: %f", DEGREESTORADIANS(45));

            

              
UIView *view = [[UIView alloc] init];
...
//Add a white border 
view.layer.borderColor = [UIColor colorWithWhite:1.0f alpha:1.0f].CGColor;
view.layer.borderWidth = 1.0f; //make border 1px thick

            

              
self.navigationItem.titleView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"ifox_logo.png"]];

            

              
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
         //Code executé dans un autre thread
        dispatch_async(dispatch_get_main_queue(), ^{
             //ici, on est dans le main thread.
        });
    });

            

              
CGRect myImageRect = CGRectMake(0.0f, 0.0f, 320.0f, 109.0f);
UIImageView *myImage = [[UIImageView alloc] initWithFrame:myImageRect];
[myImage setImage:[UIImage imageNamed:@"myImage.png"]];
myImage.opaque = YES; // explicitly opaque for performance
[self.view addSubview:myImage];
[myImage release];

            

              
CGRect webFrame = CGRectMake(0.0, 0.0, 320.0, 460.0);
UIWebView *webView = [[UIWebView alloc] initWithFrame:webFrame];
[webView setBackgroundColor:[UIColor whiteColor]];
NSString *urlAddress = @"http://www.google.com";
NSURL *url = [NSURL URLWithString:urlAddress];
NSURLRequest *requestObj = [NSURLRequest requestWithURL:url];
[webView loadRequest:requestObj];
[self addSubview:webView]; 
[webView release];

            

              
UIApplication* app = [UIApplication sharedApplication];
app.networkActivityIndicatorVisible = YES; // to stop it, set this to NO

            

              
NSArray *myImages = [NSArray arrayWithObjects:
    [UIImage imageNamed:@"myImage1.png"],
    [UIImage imageNamed:@"myImage2.png"],
    [UIImage imageNamed:@"myImage3.png"],
    [UIImage imageNamed:@"myImage4.gif"],
    nil];

UIImageView *myAnimatedView = [UIImageView alloc];
[myAnimatedView initWithFrame:[self bounds]];
myAnimatedView.animationImages = myImages;
myAnimatedView.animationDuration = 0.25; // seconds
myAnimatedView.animationRepeatCount = 0; // 0 = loops forever
[myAnimatedView startAnimating];
[self addSubview:myAnimatedView];
[myAnimatedView release];

            

              
CABasicAnimation *theAnimation; 
theAnimation=[CABasicAnimation animationWithKeyPath:@"transform.translation.x"];
theAnimation.duration=1;
theAnimation.repeatCount=2;
theAnimation.autoreverses=YES;
theAnimation.fromValue=[NSNumber numberWithFloat:0];
theAnimation.toValue=[NSNumber numberWithFloat:-60];
[view.layer addAnimation:theAnimation forKey:@"animateLayer"];

            

              
//vibreur
AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);

//son
SystemSoundID pmph;
id sndpath = [[NSBundle mainBundle] 
    pathForResource:@"mySound" 
    ofType:@"wav" 
    inDirectory:@"/"];
CFURLRef baseURL = (CFURLRef) [[NSURL alloc] initFileURLWithPath:sndpath];
AudioServicesCreateSystemSoundID (baseURL, &pmph);
AudioServicesPlaySystemSound(pmph); 
[baseURL release];

            

              
[NSThread detachNewThreadSelector:@selector(myMethod) 
        toTarget:self 
        withObject:nil];


(void)myMethod {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

*** code that should be run in the new thread goes here ***

[pool release];
}


//Si vous voulez modifier l'UI, ou executer du code dans le main thread depuis n'importe quel thread:
[self performSelectorOnMainThread:@selector(myMethod) 
    withObject:nil 
    waitUntilDone:false];

            

              
[NSTimer scheduledTimerWithTimeInterval:1 
    target:self 
    selector:@selector(myMethod:) 
    userInfo:myObject //nil si pas de paramètre à passer
    repeats:YES];

-(void)myMethod:(NSTimer*)timer {
    // Now I can access all the properties and methods of myObject
    [[timer userInfo] myObjectMethod];
}

//Pour stopper le timer
[myTimer invalidate];
myTimer = nil; // Il faut s'assurer de ne jamais appeler invalidate sur un timer déjà invalidé

            

              
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"An Alert!" 
        delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[alert show];
[alert release]; //sauf si vous utilisez ARC

            

              
// Look in Documents for an existing plist file
NSArray *paths = NSSearchPathForDirectoriesInDomains(
    NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
myPlistPath = [documentsDirectory stringByAppendingPathComponent: 
    [NSString stringWithFormat: @"%@.plist", plistName] ];
[myPlistPath retain];

// If it's not there, copy it from the bundle
NSFileManager *fileManger = [NSFileManager defaultManager];
if ( ![fileManger fileExistsAtPath:myPlistPath] ) {
    NSString *pathToSettingsInBundle = [[NSBundle mainBundle] 
        pathForResource:plistName ofType:@"plist"];
}   

//Maintenant on lit le plist depuis les documents
NSArray *paths = NSSearchPathForDirectoriesInDomains(
    NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectoryPath = [paths objectAtIndex:0];
NSString *path = [documentsDirectoryPath 
    stringByAppendingPathComponent:@"myApp.plist"];
NSMutableDictionary *plist = [NSDictionary dictionaryWithContentsOfFile: path];

//On peut lire des entrées et les modifier
myKey = (int)[[plist valueForKey:@"myKey"] intValue];
myKey2 = (bool)[[plist valueForKey:@"myKey2"] boolValue];

[plist setValue:myKey forKey:@"myKey"];
[plist writeToFile:path atomically:YES];

            

              
CGRect newInfoButtonRect = CGRectMake(infoButton.frame.origin.x-25, 
    infoButton.frame.origin.y-25, infoButton.frame.size.width+50, 
    infoButton.frame.size.height+50);
[infoButton setFrame:newInfoButtonRect];

            

              
for (UIImageView *anImage in [self.view subviews]) {
    if (anImage.tag == 1) {
        // do something
    }
}