IOS multi-threaded image loading and caching

Reprinted from http://blog.csdn.net/deep_explore/article/details/8144613

Use nsoperationqueue to load images in multiple threads and cache Images

Create a class CC

#import <Foundation/Foundation.h>@interface CC : NSOperation{    NSString *url;    NSString *imageName;    UIImage *image;    UIImageView *delegate;}@property (nonatomic,retain) NSString *url;@property (nonatomic,retain)NSString *imageName;@property (nonatomic,retain)UIImage *image;@property (nonatomic,retain)UIImageView *delegate;-(void)main;-(id) initWith:(NSString *)url imageName:(NSString *)imageName delegate:(UIImageView *)delegate;@end@implementation CC@synthesize url,delegate,image,imageName;-(id) initWith:(NSString *)url imageName:(NSString *)imageName delegate:(UIImageView *)delegate{    if (self = [super init]) {        self.url = [url retain];        self.imageName = imageName;        self.delegate = delegate;    }    return self;}-(void) main{    //    NSString *cachefile = [NSTemporaryDirectory() stringByAppendingPathComponent: self.imageName];    NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:self.url]];    [data writeToFile:cachefile atomically:YES];        //    self.image = [UIImage imageWithData:data];    [self performSelectorOnMainThread:@selector(ok) withObject:nil waitUntilDone:NO];}-(void)ok{    [self.delegate setImage:self.image]}@end

Then, call

 

// The initialization queue of the member to the column = [[nsoperationqueue alloc] init]; // The image resources are in the array arry = [nsarray arraywithobjects: @ "http://static2.dmcdn.net/static/video/451/838/44838154:jpeg_preview_small.jpg? 20120509163826 ", @" http://static2.dmcdn.net/static/video/656/177/44771656:jpeg_preview_small.jpg? 20120509154705 ", @" http://static2.dmcdn.net/static/video/629/228/44822926:jpeg_preview_small.jpg? 20120509181018 ", @" http://static2.dmcdn.net/static/video/116/367/44763611:jpeg_preview_small.jpg? 20120509101749 ", @" http://static2.dmcdn.net/static/video/340/086/44680043:jpeg_preview_small.jpg? 20120509180118 ", @" http://static2.dmcdn.net/static/video/666/645/43546666:jpeg_preview_small.jpg? 20120412153140 ", @" http://static2.dmcdn.net/static/video/771/577/44775177:jpeg_preview_small.jpg? 20120509183230 ", @" http://static2.dmcdn.net/static/video/810/508/44805018:jpeg_preview_small.jpg? 20120508125339 ", @" http://static2.dmcdn.net/static/video/152/008/44800251:jpeg_preview_small.jpg? 20120508103336 ", @" http://static2.dmcdn.net/static/video/694/741/35147496:jpeg_preview_small.jpg? 20120508111445 ", @" http://static2.dmcdn.net/static/video/988/667/44766889:jpeg_preview_small.jpg? 20120508130425 ", @" http://static2.dmcdn.net/static/video/282/467/44764282:jpeg_preview_small.jpg? 20120507130637 ", @" http://static2.dmcdn.net/static/video/754/657/44756457:jpeg_preview_small.jpg? 20120507093012 ", @" http://static2.dmcdn.net/static/video/831/107/44701138:jpeg_preview_small.jpg? 20120506133917 ", @" http://static2.dmcdn.net/static/video/411/057/44750114:jpeg_preview_small.jpg? 20120507014914 ", @" http://static2.dmcdn.net/static/video/894/547/44745498:jpeg_preview_small.jpg? 20120509183004 ", @" http://static2.dmcdn.net/static/video/082/947/44749280:jpeg_preview_small.jpg? 20120507015022 ", @" http://static2.dmcdn.net/static/video/833/347/44743338:jpeg_preview_small.jpg? 20120509183004 ", @" http://static2.dmcdn.net/static/video/683/666/44666386:jpeg_preview_small.jpg? 20120505111208 ", nil]; implement image loading in tableview-(uitableviewcell *) tableview :( uitableview *) tableview cellforrowatindexpath :( nsindexpath *) indexpath {nsstring * identifity = [nsstring stringwithformat: @ "identify % d", indexpath. section, indexpath. row]; uitableviewcell * cell = (uitableviewcell *) [tableview metadata: identifity]; If (cell = nil) {Cell = [[uitableviewcell alloc] initwithstyle: Invalid reuseidentifier: identifity]; cell. selectionstyle = uitableviewcellselectionstylenone; nsstring * filename = [nsstring stringwithformat: @ "% d", indexpath. row]; nslog (@ "FILENAME ===%@", filename); nsstring * cachefile = [nstemporarydirectory () stringbyappendingpathcomponent: Filename]; nslog (@ "cachefile =======----- % @", cachefile); uiimage * image = [uiimage imagewithcontentsoffile: cachefile]; If (image) {Cell. imageview. image = image; nslog (@ "cache available,") ;}else {nslog (@ "no cache,"); nslog (@ "arry ==% @", [arry objectatindex: indexpath. row]); CC * o = [[CC alloc] initwith: [[arry retain] objectatindex: indexpath. row] imagename: [nsstring stringwithformat: @ "% d", indexpath. row] delegate: cell. imageview]; [queue addoperation: O]; cell. imageview. image = [uiimage imagenamed: @ "default.png"]; // remember that arry requires a retain. Otherwise, the memory will crash when sliding back. [[arry retain] objectatindex: indexpath. row] This is correct }}

How to delete image Cache

# Define k_location_img_count 200 + (void) checklocationimgandremove {nsstring * apppath = [nshomedirectory () stringbyappendingstring: @ "/documents/images/permanentstore/"]; nsfilemanager * manager = [nsfilemanager defaultmanager]; If ([Manager fileexistsatpath: apppath]) {nsarray * locationimgarray = [Manager contentsofdirectoryatpath: apppath error: Nil]; if ([locationimgarray count]> [k_location_img_count Intvalue]) {[Manager removeitematpath: apppath error: Nil] ;}}@ "/documents/images/permanentstore/" custom, which is the path of the folder for caching images!

Clear cache in webview

Http://stackoverflow.com/questions/2523435/how-to-clear-uiwebview-cache