我正在使用Soap API，它将在XML文件中返回我存储在SQLite数据库中的xml文件的响应。该xml文件由图像url组成，我正在下载这些图像并将它们存储到本地文件夹中。但是下载和存储在本地文件夹中需要花费很多时间。现在我想要的是速度下载的逻辑并将它们存储在本地文件夹中。
这是我的代码：
if (categoryArray.count > 0)
NSString *stringPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)objectAtIndex:0]stringByAppendingPathComponent:@"WordImages"];
NSError *error = nil;
if (![[NSFileManager defaultManager] fileExistsAtPath:stringPath])
[[NSFileManager defaultManager] createDirectoryAtPath:stringPath withIntermediateDirectories:NO attributes:nil error:&error];
NSString *fileName = [stringPath stringByAppendingPathComponent:[NSString stringWithFormat:@"Image%lu.jpg",(unsigned long)categoryTitleArray.count]];
NSString *imgUrl = [categoryArray objectAtIndex:0];
imgUrl = [imgUrl stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imgUrl]];
[data writeToFile:fileName atomically:YES];
categoryArray = [[NSMutableArray alloc]init];
[imageArray addObject:fileName];