UIViewController

originally in view of A controller,

then show view of B controller:

[self presentModalViewController:testViewController animated:YES];

[testViewController release];

jump back to view of A controller

[self dismissModelViewControllerAnimated:YES];

UIButton

ex:

UIButton *backButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];

backButton.frame = CGRectMake(380, 260, 80, 30);

[backButton setTitle:@"Back" forState:UIControlStateNormal];

[backButton addTarget:self action:@selector(backButtonClicked:)

forControlEvents:UIControlEventTouchUpInside];

core animation

three basic steps for core animation:

1. beginAnimations

2. setAnimationDuration

3. commitAnimations

shorter word to access app delegate

#define AppDelegate (MyAppDelegate *)[[UIApplication sharedApplication] delegate]

then use AppDelegate in the code

do something in the future

1. execute function in the future

- (void)performSelector:(SEL)aSelector withObject:(id)anArgument afterDelay:(NSTimeInterval)delay;

ex: [self performSelector:@selector(sing:) withObject:nil afterDelay:1.4];

2. use timer

(NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

ex: [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(test:) userInfo:nil repeats:YES];

note:

to delete timer, use invalidate method

ex:

-(void)test:(NSTimer*)timer

{

[timer invalidate];

}

iphone view size

UIInterfaceOrientationLandscapeLeft:

w:480 h:320

modify view class for view controller

from view controller's xib,

click on view,

from inspector panel, click information ,

change class to the view class you want

game kit bluetooth connection problem

try

method 1:

turn off wifi

method 2:

restart iphone

trigger iphone vibrate

1. include AudioToolBox.framework

2.

#import

AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);

save image in the database

link:

http://www.iphonesdkarticles.com/2009/02/sqlite-tutorial-saving-images-in.html

get current time

NSCalendar *calendar= [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSCalendarUnit unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |

NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit |

NSSecondCalendarUnit;

NSDate *date = [NSDate date];

NSDateComponents *dateComponents = [calendar components:unitFlags

fromDate:date];

NSInteger year = [dateComponents year];

NSInteger month = [dateComponents month];

NSInteger day = [dateComponents day];

NSInteger hour = [dateComponents hour];

NSInteger minute = [dateComponents minute];

[calendar release];

animation delegate

1. initial

// if want to change something, such as move a UIImageView,

// then pass this UIImageView as context argument

[UIView beginAnimations:@"test" context:nil];

[UIView setAnimationDelegate:self];

[UIView setAnimationDidStopSelector:

@selector(animationDidStop:finished:context:)];

[UIView commitAnimations];

2. when animation finish, animationDidStop is called

- (void)animationDidStop:(NSString *)animationID finished:(NSNumber *)finished

context:(void *)context

NSThread

do sth on main thread , and wait until done

ex:

[self performSelectorOnMainThread:@selector(loadPhoto) withObject:nil waitUntilDone:YES];