我试图以编程方式创建一个xls表.为了填写表格,我在100左右制作了多个NSURLConnection.现在,我的方法是：
>建立连接并将数据存储到数组中.该数组有100个对象.
>现在取第一个对象并调用连接.存储数据.并在数组中与第二个对象建立第二个连接.这将持续到阵列中的最后一个对象.
完成100个连接平均需要14秒.有没有办法实现NSURLConnection以更快的方式获得响应？
直到昨天我遵循的基本方法如下：
声明属性：
@property (nonatomic,strong) NSURLConnection *getReportConnection; @property (retain,nonatomic) NSMutableData *receivedData; @property (nonatomic,strong) NSMutableArray *reportArray;
在viewDidLoad中初始化数组：
reportArray=[[NSMutableArray alloc]init];
在按钮操作中初始化NSURLConnection：
/initialize url that is going to be fetched. NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"****/%@/crash_reasons",ID]]; //initialize a request from url NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url]; [request addValue:tokenReceived forHTTPHeaderField:@"**Token"]; [request setHTTPMethod:@"GET"]; [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"]; //initialize a connection from request self.getReportConnection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
处理收到的数据：
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData*)data{
if (connection==_getVersionConnection) {
[self.receivedData_ver appendData:data];
NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSError *e = nil;
NSData *jsonData = [responseString dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *JSON = [NSJSONSerialization JSONObjectWithData:jsonData options: NSJSONReadingMutableContainers error: &e];
[JSON[@"app_versions"] enumerateObjectsUsingBlock:^(id obj,NSUInteger idx,BOOL *stop) {
if (![obj[@"id"] isEqual:[NSNull null]] && ![reportArray_ver containsObject:obj[@"id"]]) {
[reportArray_ver addObject:obj[@"id"]];
}
NSLog(@"index = %lu,Object For title Key = %@",(unsigned long)idx,obj[@"id"]);
}];
if (JSON!=nil) {
UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"Version Reports succesfully retrieved" message:@"" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
[alert show];
}
}
}
完成后调用另一个连接：
// This method is used to process the data after connection has made successfully.
- (void)connectionDidFinishLoading:(NSURLConnection *)connection{
if (connection==getReportConnection) {
//check and call the connection again
}
}
今天,我尝试使用sendAsync的NSURLConnection一个接一个地使用循环触发所有连接,并且它工作得很好.
self.receivedData_ver=[[NSMutableData alloc]init];
__block NSInteger outstandingRequests = [reqArray count];
for (NSString *URL in reqArray) {
NSMutableURLRequest *request=[NSMutableURLRequest requestWithURL:[NSURL URLWithString:URL]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:10.0];
[request setHTTPMethod:@"GET"];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[NSURLConnection sendAsynchronousRequest:request
queue:[NSOperationQueue mainQueue]
completionHandler:^(NSURLResponse *response,NSData *data,NSError *connectionError) {
[self.receivedData appendData:data]; //What is the use of appending NSdata into Nsmutable data?
NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSError *e = nil;
NSData *jsonData = [responseString dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *JSON = [NSJSONSerialization JSONObjectWithData:jsonData options: NSJSONReadingMutableContainers error: &e];
NSLog(@"login json is %@",JSON);
[JSON[@"app_versions"] enumerateObjectsUsingBlock:^(id obj,BOOL *stop) {
if (![obj[@"id"] isEqual:[NSNull null]] && ![reportArray_ver containsObject:obj[@"id"]]) {
[reportArray_ver addObject:obj[@"id"]];
}
NSLog(@"index = %lu,obj[@"id"]);
}];
outstandingRequests--;
if (outstandingRequests == 0) {
//all req are finished
UIAlertView *alert=[[UIAlertView alloc]initWithTitle:@"Version Reports succesfully retrieved" message:@"" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles: nil];
[alert show];
}
}];
}
这次花了一半的时间来完成100个请求而不是旧的过程,除了asynReq之外还有更快的方法吗？.使用NSURLconnection和NSURLConnection与asyncReq的最佳方案是什么？
解决方法
几点意见：
>使用NSURLSession而不是NSURLConnection(如果您支持7.0及更高版本的iOS版本)：
for (NSString *URL in URLArray) {
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
// configure the request here
// now issue the request
NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data,NSURLResponse *response,NSError *error) {
// check error and/or handle response here
}];
[task resume];
}
>如果您绝对必须发出100个请求,那么请像sendAsynchronousRequest实现(或我的dataTaskWithRequest)一样同时发出它们,而不是顺序发出.这就是实现巨大性能优势的原因.
但请注意,您无法保证它们完全按照您发布的顺序,因此您将需要使用一些支持它的结构(例如,使用NSMutableDictionary或使用占位符预填充NSMutableArray,以便您可以更新特定索引处的条目,而不是将项添加到数组中).
最重要的是,请注意它们可能无法按照要求完成相同的顺序,因此请确保妥善处理.
>如果您保留100个单独的请求,我建议您在非常慢的网络连接上进行测试(例如,使用网络链路调节器来模拟真正糟糕的网络连接;请参阅NSHipster discussion).只有在慢速连接时才会出现问题(超时,UI打嗝等).
>我建议使用调度组或操作队列依赖项,而不是减少待处理请求数的计数器.
dispatch_group_t group = dispatch_group_create();
for (NSString *URL in URLArray) {
dispatch_group_enter(group);
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:URL];
// configure the request here
// now issue the request
NSURLSessionTask *task = [[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:^(NSData *data,NSError *error) {
// check error and/or handle response here
// when all done,leave group
dispatch_group_leave(group);
}];
[task resume];
}
dispatch_group_notify(group,dispatch_get_main_queue(),^{
// do whatever you want when all of the requests are done
});
>如果可能,请查看是否可以重构Web服务,以便发出一个返回所有数据的请求.如果您正在寻求进一步的性能改进,那可能就是这样做的方式(并且它避免了在发出100个单独请求时涉及的许多复杂性).
>顺便说一句,如果您使用基于委托的连接,就像在原始问题中所做的那样,您不应该在didReceiveData中解析数据.这应该只是将数据附加到NSMutableData.在connectionDidFinishLoading委托方法中进行所有解析.
如果你去基于块的实现,这个问题就会消失,但只是观察你的代码片段.
