Simple page turning

Http://marshal.easymorse.com/archives/3760

The page flip effect is similar to the following:

It is common in e-book applications. There are two key points:

• Flip Animation
• Processing of swipe

 

Let's talk about the implementation of swipe. You can refer to the simple gesture example: tap to understand the gesture types.

In the viewdidload method, you have registered four easy handling methods in the upper, lower, left, and right directions:

-(Void) viewdidload {

Uiswipegesturerecognizer * recognizer;

Recognizer = [[uiswipegesturerecognizer alloc] initwithtarget: Self action: @ selector (handleswipefrom :)];
[Recognizer setdirection :( uiswipegesturerecognizerdirectionright)];
[[Self view] addgesturerecognizer: recognizer];
[Recognizer release];

Recognizer = [[uiswipegesturerecognizer alloc] initwithtarget: Self action: @ selector (handleswipefrom :)];
[Recognizer setdirection :( uiswipegesturerecognizerdirectionup)];
[[Self view] addgesturerecognizer: recognizer];
[Recognizer release];

Recognizer = [[uiswipegesturerecognizer alloc] initwithtarget: Self action: @ selector (handleswipefrom :)];
[Recognizer setdirection :( uiswipegesturerecognizerdirectiondown)];
[[Self view] addgesturerecognizer: recognizer];
[Recognizer release];

Recognizer = [[uiswipegesturerecognizer alloc] initwithtarget: Self action: @ selector (handleswipefrom :)];
[Recognizer setdirection :( uiswipegesturerecognizerdireleft left)];
[[Self view] addgesturerecognizer: recognizer];
[Recognizer release];


[Super viewdidload];

We can see that handleswipefrom is the same method.

In this method, we can identify the specific direction of the light scanning gesture, for example, to determine the downward light scanning:

-(Void) handleswipefrom :( uiswipegesturerecognizer *) recognizer {
Nslog (@ "swipe received .");

If (recognizer. Direction = uiswipegesturerecognizerdirectiondown ){
Nslog (@ "swipe down ");

Check whether the scan is upward:

If (recognizer. Direction = uiswipegesturerecognizerdirectionup ){
Nslog (@ "swipe up ");

 The processing of animations, such as turning pages down (back), is similar to the following:

[Uiview beginanimations: @ "animationid" context: Nil];
[Uiview setanimationduration: 0.7f];
[Uiview setanimationcurve: uiviewanimationcurveeaseinout];
[Uiview setanimationrepeatautoreverses: No];
[Uiview setanimationtransition: uiviewanimationtransitioncurldown forview: Self. View cache: Yes];

[Currentview removefromsuperview];
[Self. View addsubview: contentview];

[Uiview commitanimations];

To flip the page up (forward), you only need to change:

[Uiview beginanimations: @ "animationid" context: Nil];
[Uiview setanimationduration: 0.7f];
[Uiview setanimationcurve: uiviewanimationcurveeaseinout];
[Uiview setanimationrepeatautoreverses: No];
[Uiview setanimationtransition:UiviewanimationtransitioncurlupForview: Self. View cache: Yes];

[Currentview removefromsuperview];
[Self. View addsubview: contentview];

[Uiview commitanimations];

 For an e-book, you also need to consider the problem of having multiple pages (images), such as 50 pages. A Data Structure is required to store the image paths of these pages:

• Objc data structure, such as array
• SQLite database table

In this way, write a set of flip pagesCodeIt can be decoupled from the loaded image.

In this example, an array is used, similar to the following:

Pages = [[nsarray alloc] initwithobjects: @ "1.jpg", @" 2.jpg", @ "3.jpg", @" 4.jpg", @ "5.jpg", @" 6.jpg ",
Nil];

Save the image to resources.

The following mechanism is used to locate the associated page when turning pages on the previous page and the next page:

• Encapsulate the image as uiimageview display
• You can set a tag value for uiimageview. The value is array subscript + 1.
• In this way, the higher-level view can query uiimageview by TAG, for example, uiview * currentview = [self. View viewwithtag: currenttag];
• Sets a member variable currenttag to save the current tag value.

For example, when an application is loaded, the first page is displayed:

currenttag = 1;
nsstring * Path = [[nsbundle mainbundle] pathforresource: @ "pageflip1" oftype: @ "MP3"];
player = [[avaudioplayer alloc] initwithcontentsofurl: [nsurl fileurlwithpath: path] error: NULL];
// [[uiapplication sharedapplication] setstatushidbarden: yes animated: No];
[[uiapplication sharedapplication] setstatusbarhidden: Yes withanimation: uistatusbaranimationslide];
uiimageview * contentview = [uiimageview alloc] initwithframe: [[uiscreen mainscreen] applicationframe];
[contentview setimage: [uiimage imagenamed: [Pages objectatindex :( currentTag-1)];
[contentview setuserinteractionenabled: Yes];
contentview. tag = currenttag;

Processing during page turning:

If (currenttag <[Pages count]) {
Uiview * currentview = [self. View viewwithtag: currenttag];
Currenttag ++;

Uiimageview * contentview = [[uiimageview alloc] initwithframe: [uiscreen mainscreen] applicationframe];
[Contentview setimage: [uiimage imagenamed: [Pages objectatindex :( currentTag-1)];
[Contentview setuserinteractionenabled: Yes];
Contentview. Tag = currenttag;

[Uiview beginanimations: @ "animationid" context: Nil];
[Uiview setanimationduration: 0.7f];
[Uiview setanimationcurve: uiviewanimationcurveeaseinout];
[Uiview setanimationrepeatautoreverses: No];
[Uiview setanimationtransition: uiviewanimationtransitioncurlup forview: Self. View cache: Yes];

[Currentview removefromsuperview];
[Self. View addsubview: contentview];

[Uiview commitanimations];