The Uicollectionview of IOSDay34

1. What is a collection view

After iOS6.0 , Apple introduced a new view that inherits from the Uiscrollview , Uicollectionview , also known as the Collection View . Common with UITableView as the two views commonly used in development, often appearing as the main interface of the project

2. Create Uicollectionview　
The realization of 1> Uicollectionview

u Icollectionview is implemented with tableview is not the same place layout a little more complicated , need uicollectionviewlayout the class to describe the layout of the view's view. What we commonly use in our projects is the system-provided uicollectionviewflowerlayout class, you can also customize uicollectionviewlayout

2> Creating uicollectionviewflowerlayout

1     //1. Define the style of the CollectionView2     3Self.myflowlayout = [UicollectionviewflowlayoutNew];4     //Setting Properties5     //the size of the given item6Self.myFlowLayout.itemSize = Cgsizemake ((Kwidth- +) /3, Kwidth/3);7     //minimum gap between two item (vertical scrolling)8Self.myFlowLayout.minimumInteritemSpacing =Ten;9     //minimum gap (horizontal scrolling) between each two itemTenSelf.myFlowLayout.minimumLineSpacing =Ten; One     //Set Scroll Direction ASelf.myFlowLayout.scrollDirection = uicollectionviewscrolldirectionvertical;//Vertical Direction - //self.myFlowLayout.scrollDirection = uicollectionviewscrolldirectionhorizontal;//Horizontal Direction -     //set the inner margin of the view (top left and bottom right) theSelf.myFlowLayout.sectionInset = Uiedgeinsetsmake ( -,Ten,Ten,Ten); -      -     //Layout Head View dimensions -Self.myFlowLayout.headerReferenceSize = Cgsizemake (0, -); +      -     //layout tail View dimensions +Self.myFlowLayout.footerReferenceSize = Cgsizemake (0, -);

3> Initialize uicollectionview

1     // 2. Layout CollectionView 2     // create an object and specify a style 3     Self.collectionview = [[Uicollectionview alloc] initWithFrame:self.bounds collectionviewlayout: Self.myflowlayout]; 4     5     Self.collectionView.backgroundColor = [Uicolor cyancolor]; 6     7     [Self addSubview:self.collectionView];

4> setting up Agents

    // set up proxy    Self.rootView.collectionView. delegate = self ;     = self;

5> Register Cell

    // First step: Register the cell    class] Forcellwithreuseidentifier:identifier_cell];

6> Proxy Method

　　① uicollectionview and UITableView have two proxy methods that must be implemented

Returns the number of Item

1 // set the number of item per partition 2 -(Nsinteger) CollectionView: (Uicollectionview *) CollectionView numberofitemsinsection: (NSInteger) Section3{4     return; 5 }

Specify the style for each Item

1 //returns a Cell object for each item2-(Uicollectionviewcell *) CollectionView: (Uicollectionview *) CollectionView Cellforitematindexpath: (NSIndexPath *) Indexpath3 {4Rootcell *cell =[CollectionView Dequeuereusablecellwithreuseidentifier:identifier_cell Forindexpath:indexpath];5     6Cell.backgroundcolor =[Uicolor Redcolor];7     8     if(0==indexpath.section) {9Cell.photoImage.image = [UIImage imagenamed:@"1"];Ten     } One     if(1==indexpath.section) { ACell.photoImage.image = [UIImage imagenamed:@"2"]; -     } -     if(2==indexpath.section) { theCell.photoImage.image = [UIImage imagenamed:@"3"]; -     } -      -     returncell; +}

Rootcell for custom cells　　

② choosing an implemented proxy method

Uicollectionview has a number of proxy methods that you can choose to implement, such as:

• To set the number of partitions:

1 // returns the number of groups 2 -(Nsinteger) Numberofsectionsincollectionview: (Uicollectionview *) CollectionView3 {4     return 3 ; 5 }

• Item click Method

1 // Click on item 2 -(void) CollectionView: (Uicollectionview *) CollectionView Didselectitematindexpath: ( Nsindexpath *) Indexpath3{4     new]; 5     6     [Self.navigationcontroller PUSHVIEWCONTROLLER:SECONDVC animated:yes]; 7 }

• Returns the style of the head, tail view

Uicollectionview can not directly specify the head and tail view as the UITableView , need to register use , the biggest benefit is to add the reuse mechanism .

1     //Register Head View2[Self.rootView.collectionView Registerclass:[headerreusableviewclass] Forsupplementaryviewofkind:uicollectionelementkindsectionheader Withreuseidentifier:@"Headerview"];3     4     //Register Tail View5[Self.rootView.collectionView Registerclass:[uicollectionreusableviewclass] Forsupplementaryviewofkind:uicollectionelementkindsectionfooter Withreuseidentifier:@"Footerview"];6 //return to head view and tail view7-(Uicollectionreusableview *) CollectionView: (Uicollectionview *) CollectionView Viewforsupplementaryelementofkind :(NSString *) kind Atindexpath: (Nsindexpath *) Indexpath8 {9     //judge whether the head view or the tail viewTen     if([Kind Isequaltostring:uicollectionelementkindsectionheader]) { One          AHeaderreusableview *headerview = [CollectionView dequeuereusablesupplementaryviewofkind:kind withReuseIdentifier:@"Headerview"Forindexpath:indexpath]; -          - //Headerview.backgroundcolor = [Uicolor redcolor]; the          -         Switch(indexpath.section) { -              Case 0: -HeaderView.headerLabel.text =@"Student Period"; +                  Break; -              Case 1: +HeaderView.headerLabel.text =@"Life Time"; A                  Break; at              Case 2: -HeaderView.headerLabel.text =@"Programmer"; -                  Break; -             default: -                  Break; -         } in         returnHeaderview; -     } to      +Uicollectionreusableview *footerview = [CollectionView dequeuereusablesupplementaryviewofkind: Uicollectionelementkindsectionfooter Withreuseidentifier:@"Footerview"Forindexpath:indexpath]; -Footerview.backgroundcolor =[Uicolor Lightgraycolor]; the      *     returnFooterview; $}

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3. Layout Protocol

Layout protocol: Uicollectionviewdelegateflowlayout , which is an extension to uicollectionviewdelegate

The Uicollectionview of IOSDay34