ios 从网络下载图片，保存，并用imageview从保存中显示

-(UIImage *) getImageFromURL:(NSString *)fileURL {
    NSLog(@"执行图片下载函数");
    UIImage * result;
    
    NSData * data = [NSData dataWithContentsOfURL:[NSURL URLWithString:fileURL]];
    result = [UIImage p_w_picpathWithData:data];
    
    return result;
}
-(void) saveImage:(UIImage *)p_w_picpath withFileName:(NSString *)p_w_picpathName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    if ([[extension lowercaseString] isEqualToString:@"png"]) {
        [UIImagePNGRepresentation(p_w_picpath) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", p_w_picpathName, @"png"]] options:NSAtomicWrite error:nil];
    } else if ([[extension lowercaseString] isEqualToString:@"jpg"] || [[extension lowercaseString] isEqualToString:@"jpeg"]) {
        [UIImageJPEGRepresentation(p_w_picpath, 1.0) writeToFile:[directoryPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.%@", p_w_picpathName, @"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");
    }
}
-(UIImage *) loadImage:(NSString *)fileName ofType:(NSString *)extension inDirectory:(NSString *)directoryPath {
    UIImage * result = [UIImage p_w_picpathWithContentsOfFile:[NSString stringWithFormat:@"%@/%@.%@", directoryPath, fileName, extension]];
    
    return result;
}

 NSString * documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
    NSLog(@"保存路径:%@",documentsDirectoryPath);
    //Get Image From URL
    UIImage * p_w_picpathFromURL = [self getImageFromURL:@"http://file.duteba.com/phone/2009/04/5/ftGxL8kcUL.jpg"];
    
    //Save Image to Directory
    [self saveImage:p_w_picpathFromURL withFileName:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath];
    
    //Load Image From Directory
    UIImage * p_w_picpathFromWeb = [self loadImage:@"MyImage" ofType:@"jpg" inDirectory:documentsDirectoryPath];
    [img setImage:p_w_picpathFromWeb];
    
    //取得目录下全部文件名
    NSArray *file = [[[NSFileManager alloc] init] subpathsAtPath:documentsDirectoryPath];
    //NSLog(@"%d",[file count]);
    NSLog(@"%@",file);
    
    //如何获取下载的文件的完整路径?

把已经下载的jpg用p_w_picpathview显示

 NSString *documentsDirectory2 = [path2 objectAtIndex:0]; //path数组里貌似只有一个元素
    //字符串拼接获得文件完整路径
    NSString *filestr = @"/MyImage.jpg";
    NSString *newstr = [documentsDirectory2 stringByAppendingString:filestr];
    NSLog(@"完整路径是:%@",newstr);
    
    NSData *dd = [NSData dataWithContentsOfFile:newstr];
    [img222 setImage:[UIImage p_w_picpathWithData:dd]];