//从网络下载图片-(UIImage *) getImageFromURL:(NSString *)fileURL {    NSLog(@"执行图片下载函数");    UIImage * result;    NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]];    result = [UIImage imageWithData:data];    return result;}//将所下载的图片保存到本地-(void) saveImage:(UIImage *)image withFileName:(NSString *)imageName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {    if ([[extension lowercaseString] isEqualToString:@"png"]) {        [UIImagePNGRepresentation(image) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"png"]] options:NSAtomicWrite error:nil];    } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) {        [UIImageJPEGRepresentation(image, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", imageName, @"jpg"]] options:NSAtomicWrite error:nil];    } else {        //ALog(@"Image Save Failed\\nExtension: (%@) is not recognized, use (PNG/JPG)", extension);        NSLog(@"文件后缀不认识");    }}//读取本地保存的图片-(UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {    UIImage * result = [UIImage imageWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, extension]];    return result;}//从网络下载图片，保存，并用 UIImageView 从保存中显示NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];    NSLog(@"保存路径:%@",documentsDirectoryPath);    //Get Image From URL    UIImage * imageFromURL = [self getImageFromURL:@"http://file.duteba.com/phone/2009/04/5/ftGxL8kcUL.jpg"];    //Save Image to Directory    [self saveImage:imageFromURL withFileName:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath];    //Load Image From Directory    UIImage * imageFromWeb = [self loadImage:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath];    [img setImage:imageFromWeb];    //取得目录下所有文件名    NSArray *file = [[[NSFileManager alloc] init] subpathsAtPath:documentsDirectoryPath];    //NSLog(@"%d",[file count]);    NSLog(@"%@",file);//该片段来自于http://outofmemory.cn

网络图片方案