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问题描述
我在类方法中有以下代码
I have the following bit of code in a class method
NSDictionary *shopAddresses = [[NSDictionary alloc] initWithContentsOfFile:fileName]; NSMutableArray *shopLocations = [NSMutableArray arrayWithCapacity:shopAddresses.count]; [shopAddresses enumerateKeysAndObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id key, ShopLocation *shopLocation, BOOL *stop) { CLGeocoder *geocoder = [[CLGeocoder alloc] init]; [geocoder geocodeAddressString:shopLocation.address completionHandler:^(NSArray *placemarks, NSError *error) { if (error) { NSLog(@"Geocode failed with error: %@", error); } else { shopLocation.placemark = [placemarks objectAtIndex:0]; } [shopLocations addObject:shopLocation]; }]; }执行此代码后,我想返回shopLocations数组作为结果对于该方法。但是,如果我不希望数组为空,我需要等待所有地理编码器搜索完成。
After execution of this code, I want to return the shopLocations array as a result for the method. However I need to somehow wait until all geocoder searches have finished if I don't want the array to be empty.
我该怎么做?
我尝试了不同的GCD方法,但没有成功远。
I have tried different GCD approaches, but haven't been successful so far.
推荐答案这可以通过 dispatch_group _... 函数来处理:
This can be handled by the dispatch_group_... functions:
… dispatch_group_t group = dispatch_group_create(); [shopAddresses enumerateObjectsUsingBlock:^(id key, NSUInteger idx, BOOL *stop) { dispatch_group_enter(group); CLGeocoder *geocoder = [[CLGeocoder alloc] init]; [geocoder geocodeAddressString:shopLocation.address completionHandler:^(NSArray *placemarks, NSError *error) { if (error) { NSLog(@"Geocode failed with error: %@", error); } else { shopLocation.placemark = [placemarks objectAtIndex:0]; } [shopLocations addObject:shopLocation]; dispatch_group_leave(group); }]; }]; while (dispatch_group_wait(group, DISPATCH_TIME_NOW)) { [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate dateWithTimeIntervalSinceNow:1.f]]; } dispatch_release(group); …我正在使用这些块积累一些网络请求。
I'm using these kind of blocks to accumulate some network requests.
我希望这可以提供帮助。
I hope this can help.
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等待CLGeocoder完成并发枚举
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