iOS Basics (23)--automatic switch between timer nstimer and pictures

First, Nstimer

Nstimer is an object that can execute the method we specify at a certain point in time from now to the back or periodically. You can send the information you make to the target object at a certain time interval. and update the behavior of an object. You can choose to stop, open, and even destroy it sometime in the future.

1, the creation of Nstimer

+ (Nstimer *) Timerwithtimeinterval: (nstimeinterval) TI target: (ID) atarget selector: (SEL) Aselector userInfo: (ID) UserInfo repeats: (BOOL) Yesorno;

+ (Nstimer *) Scheduledtimerwithtimeinterval: (nstimeinterval) TI target: (ID) atarget selector: (SEL) Aselector UserInfo :(ID) UserInfo repeats: (BOOL) Yesorno;

Note that the two methods are different;

The first method requires a manual addtimer:formode: Add a timer to a runloop:

Such as:

Nstimer *tImer = [nstimer timerwithtimeinterval: 1. 0 target:selfselector:@ Selector(timeraction:) userInfo:nil repeats: YES];

[[nsrunloop currentrunloop] addtimer: timer formode:nsdefaultrunloopmode];

The second scheduled method will be added directly to the current runloop with the default mode:

Such as:

Nstimer *timer = [Nstimer scheduledtimerwithtimeinterval:1.0 target:self selector: @selector (timeraction:) UserInfo: Nil Repeats:yes];

Several parameters:

TimerInterval : Time to wait before executing

target : The object that needs to execute the method

Selector : The method to be executed

repeats : whether to cycle

2. Release method

[Timer invalidate];

If the timer is no longer used, it is best to set nil, and if you continue to use it, you do not need to set

Timer = nil;

3. Pause/Restart of timer

The method of closing the timer above is permanent and cannot be stopped using the above stop method when the timer is paused.

Pause timer (temporarily off)

[Timer setfiredate: [nsdate distantfuture];

Turn on timer

[Timer setfiredate: [nsdate distantpast];

Second, Uiscrollview, Uipagecontrol, nstimer to achieve automatic image switching

Demo

1 @interfaceViewcontroller () <UIScrollViewDelegate>{2 3Uipagecontrol *PageCtrl;4Uiscrollview *ScrollView;5Nsarray *Imagearray;6     7Nstimer *timer;8     intLastPage;9     intcurrentpage;Ten  One } A  - @end -  the @implementationViewcontroller -  -- (void) Viewdidload { - [Super Viewdidload]; +     //additional setup after loading the view, typically from a nib. -     floatwidth =Self.view.frame.size.width; +      A     //Create Uiscrollview atScrollView = [[Uiscrollview alloc] initWithFrame: (cgrect) {0, -, Width, the}]; -ScrollView.Delegate=Self ; -scrollview.pagingenabled =YES; -Scrollview.contentsize = Cgsizemake (width*5, the); -Scrollview.showshorizontalscrollindicator =NO; -Scrollview.showsverticalscrollindicator =NO; in [Self.view Addsubview:scrollview]; -      to     //Turn on Timer method + [self timeon]; -      the     //Create Uipagecontrol *PageCtrl = [[Uipagecontrol alloc] initWithFrame: (cgrect) {0, the, Width, -}]; $ [Self.view Addsubview:pagectrl];Panax NotoginsengPagectrl.numberofpages =5; -Pagectrl.currentpageindicatortintcolor =[Uicolor Graycolor]; thePagectrl.pageindicatortintcolor = [Uicolor colorwithwhite:0.8Alpha1]; + [PageCtrl addtarget:self Action: @selector (pageaction:) forcontrolevents:uicontroleventtouchupinside]; A      the      +     floatImageWidth = width- the; -     floatImageHeight = Max; $      $Imagearray [Email protected][@"TU3",@"TU1",@"TU2",@"Tu4",@"Tu5"]; -      -     //iterate through the Imagearray array and add images to Uiscrollview the      for(intI=0; i<imagearray.count; i++) { -NSString *image =[Imagearray objectatindex:i];Wuyi          theScrollpageview *images = [[Scrollpageview alloc] initWithFrame: (cgrect) {4+width*0.5(In3, imagewidth,imageheight} setimage:[uiimage Imagenamed:image]]; - [ScrollView addsubview:images]; Wu     } - } About  $ //Automate picture Switching -- (void) changeimage{ -CurrentPage = lastpage+1; -[ScrollView Setcontentoffset: (cgpoint) {currentpage*375,0} Animated:yes]; ALastPage =currentpage; +     if(lastpage>3) { theLastPage =-1; -     } $ } the  the- (void) Scrollviewdidscroll: (Uiscrollview *) scrollview{ the     intpage = scrollview.contentoffset.x/ScrollView.frame.size.width; thePagectrl.currentpage =page; - } in  the //going to start dragging off the timer the- (void) Scrollviewwillbegindragging: (Uiscrollview *) scrollview{ About [self timeoff]; the } the  the //end Drag to open timer +- (void) Scrollviewdidenddragging: (Uiscrollview *) ScrollView willdecelerate: (BOOL) decelerate{ - [self timeon]; the }Bayi  the //Turn on Timer the- (void) timeon{ -      -Timer = [Nstimer scheduledtimerwithtimeinterval:1 the target:self the selector: @selector (changeimage) the Userinfo:nil the Repeats:yes]; -      the [[Nsrunloop Currentrunloop] Addtimer:timer formode:nsrunloopcommonmodes]; the } the 94 //Turn off the timer the- (void) timeoff{ the      the [timer invalidate];98Timer =Nil; About } - 101- (void) Pageaction: (uipagecontrol*) page{102     intPagenum = (int) Pagectrl.currentpage;103Cgsize size =scrollView.frame.size;104[ScrollView Setcontentoffset: (cgpoint) {(pagenum+1) *size.width,0} Animated:yes]; the [timer invalidate];106}

iOS Basics (23)--automatic switch between timer nstimer and pictures