Image caching for IOS tableview asynchronous loading

1. Establish a viewcontroller. H file implements Uiscrollviewdelegate and Uitableviewdelegate, and declares the ictableviewdelegate (used to implement the picture has a cache to load the picture, no cache then requests the picture and caches it and then loads it). h file as follows

#define Kimagekey @ "Photofileurl"///the  key name of the image URL for each item in the array, # define Kidkey @ "ActivityID"//    ID of each item in the array  used for caching #import <UIKit/UIKit.h> @protocol ictableviewdelegate@required    -(void) Cellimagedidload: ( Nsindexpath *) Indexpath Image: (Nsmutablearray *) Imagearray; @end @interface Ictableviewcontroller:uiviewcontroller <uiscrollviewdelegate,uitableviewdelegate>{@public    ID <WQTableViewDelegate> wqtableviedelegate;    Nsmutablearray *tabledataarray;    UITableView *wqtable;} @end

The. m file is as follows:

-(void) loadcellimage{//method implementation picture has a cache load picture, no cache then request picture and cache and then load nsarray *indexpathsforload = [Wqtable indexpathsforvisibl    Erows];        For (Nsindexpath *item in indexpathsforload) {Nsinteger Rownumberforcell = Item.row;        NSLog (@ "%li", (long) Rownumberforcell);        NSLog (@ "%li", (unsigned long) [Tabledataarray Count]);        if (Rownumberforcell >[tabledataarray count]-1) {return;        } nsstring *imagestr =tabledataarray[rownumberforcell][@ "Photofileurl"];        NSLog (@ "%@", imagestr);        Nsmutablearray *imagearray = [Nsmutablearray array];            if ([Imagestr length]!=0) {Nsarray *photourl = [Imagestr componentsseparatedbystring:multi_files_separator];  for (int i=0;i<photourl.count-1;i++) {//Display picture NSData *imagedata = [NSData Datawithcontentsofurl:[nsurl urlwithstring:[[nsstring stringwithformat:@ "%@/%@%@", [WiseApplicationViewController Getimgbucketdomain],[wiseapplicationviewcontrollER getorganizationid],photourl[i]] [stringbyaddingpercentescapesusingencoding:nsutf8stringencoding]]; NSString *imagename = [Tabledataarray[rownumberforcell][kimagekey] stringbyappendingstring:[nsstring                stringwithformat:@ ". Temp"]; NSString *imagedatapath = [Nshomedirectory () stringbyappendingpathcomponent:[@ "library/caches/"                                Stringbyappendingstring:imagename]]; if (![ [Nsfilemanager Defaultmanager] Fileexistsatpath:imagedatapath] {[ImageData writetofil                    E:imagedatapath Atomically:yes];                                        UIImage *image = [UIImage imagewithdata:imagedata];                                                        [Imagearray Addobject:image];        }} [Ictableviedelegate Cellimagedidload:item Image:imagearray]; }}} #pragma mark-table View delegate-(void) TableView: (UITableView *) TableView Willdisplaycell: (uitableViewcell *) cell Forrowatindexpath: (Nsindexpath *) Indexpath{//<span style= "font-family: ' Courier New '; White-space: Pre-wrap; Background-color:rgb (245, 245, 245); margin:0px; padding:0px; line-height:1.5!important; " > Drag </span><span style= "LINE-HEIGHT:19PX; White-space:pre-wrap; Font-family:arial, Helvetica, Sans-serif; >tableview</span><span style= "font-family: ' Courier New '; White-space:pre-wrap; Background-color:rgb (245, 245, 245); margin:0px; padding:0px; line-height:1.5!important; " > Perform </span><span style= "line-height:19px after the deceleration is completed; White-space:pre-wrap; Font-family:arial, Helvetica, Sans-serif; > Stop scrolling when start cache load picture process </span> if (!tableview.isdragging &&!tableview.isdecelerating) {[Self    Performselectorinbackground: @selector (loadcellimage) Withobject:nil]; }} #pragma mark-scroll View delegate-(void) scrollviewdidenddecelerating: (Uiscrollview *) Scrollview{//<span style= "Font-family: ' Courier New '; WHite-space:pre-wrap; Background-color:rgb (245, 245, 245); margin:0px; padding:0px; line-height:1.5!important; " > Drag <span style= "Background-color:rgb (240, 240, 240); line-height:1.5; " >scroll</span><span style= "Background-color:rgb (240, 240, 240); line-height:19px; Font-family:arial, Helvetica, Sans-serif; >view</span><span style= "margin:0px; padding:0px; line-height:1.5!important; " > After completion of deceleration when performing </span><span style= "Background-color:rgb (240, 240, 240); line-height:19px; Font-family:arial, Helvetica, Sans-serif; > Start cache load picture process </span></span> [self performselectorinbackground: @selector (loadcellimage) Withobject: NIL];} -(void) scrollviewdidenddragging: (Uiscrollview *) ScrollView willdecelerate: (BOOL) Decelerate{//<span style= " Color:rgb (51, 51, 51); Font-family:verdana, Sans-serif, song body; font-size:13px; letter-spacing:0.5px; line-height:22.5px; " > code to execute when scrolling is stopped </span> if (!decelerate) {[Self performselectoRinbackground: @selector (loadcellimage) Withobject:nil]; }}

Then the specific subclass inherits the parent class and implements the Ictableviewdelegate proxy method

#pragma mark ictableviewdelegate-(void) Cellimagedidload: (Nsindexpath *) Indexpath Image: (Nsmutablearray *) Imagearray    {Eventshowtableviewcell *cell = (Eventshowtableviewcell *) [_eventlisttableview Cellforrowatindexpath:indexpath];                if ([Imagearray count]!=0) {for (int i=0;i<imagearray.count;i++) {if (is_ios8_or_later) { Customphotobtn *photobtn = (CUSTOMPHOTOBTN *) [Cell.contentview Viewwithtag: (i + 1) *10]//<span style= "font-family: Arial, Helvetica, Sans-serif; >customphotobtn</span><span style= "font-family:arial, Helvetica, Sans-serif;" > Load a control in a picture package </span> UIImage *thumbimg = [filetransferhelp thumbnailwithimage: (UIImage *) Imagearray                [i] Size:cgsizemake (60, 40)];                [Photobtn.imgview setimage:thumbimg];            [Cell.contentview ADDSUBVIEW:PHOTOBTN];                }else{customphotobtn *photobtn = (CUSTOMPHOTOBTN *) [Cell.contentview Viewwithtag: (i + 1) *10]; UIImage *thumbimg = [Filetransferhelp thumbnailwithimage: (UIImage *) Imagearray[i] Size:cgsizemake (60, 40)];                [Photobtn.imgview setimage:thumbimg];            [Cell ADDSUBVIEW:PHOTOBTN]; }        }    }    }

Setting the contents of each cell in a subclass.

-(uitableviewcell *) TableView: (uitableview *) TableView Cellforrowatindexpath: (Nsindexpath *) Indexpath

Write it down.

Customphotobtn *photobtn = [customphotobtn customphotobtn];//loading a control in the picture package    [Photobtn.filefullname SetText:url];        NSString *imagename = [url stringbyappendingstring:[nsstring stringwithformat:@ ". Temp"];        NSLog (@ "imagename%@", imageName);    NSString *imagedatapath = [Nshomedirectory () stringbyappendingpathcomponent:[@ "library/caches/" stringbyappendingstring:imagename]]//to find the image    NSLog (@ "imagedatapath%@", Imagedatapath) from the cache;//    [data Writetofile:imagedatapath Atomically:yes];    UIImage *image = [UIImage imagewithdata:[nsdata datawithcontentsoffile:imagedatapath];    UIImage *thumbimg = [Filetransferhelp thumbnailwithimage:image size:cgsizemake (.)];    if (thumbimg) {        [Photobtn.imgview setimage:thumbimg];    }        return photobtn;

Image caching for IOS tableview asynchronous loading