我正在尝试执行三个不同的JSON连接来填充一个mapView与标记形成三个不同的MySQL表。
这是我现在要做的代码。为了测试连接，我记录了didReceiveData方法，但是编译器游标没有到达该方法，当然，地图上显示了任何标记。
请您看看我的代码，并告诉我我错过了什么或做错了。谢谢你。
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = @"Geolocalización";
//carga de datos JSON
//network activity indicator showed during downloading data
//PROCESSING FIRST CONNECTION
first_connection_url = [NSURL URLWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/empresastodaslist.php"];
NSURLRequest *first_connection_request = [NSURLRequest requestWithURL:first_connection_url];
NSURLConnection *first_connection=[[NSURLConnection alloc]initWithRequest:first_connection_request delegate:self];
//PROCESSING SECOND CONNECTION
second_connection_url = [NSURL URLWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/centrostodoslist.php"];
NSURLRequest *second_connection_request = [NSURLRequest requestWithURL:second_connection_url];
NSURLConnection *second_connection=[[NSURLConnection alloc]initWithRequest:second_connection_request delegate:self];
//PROCESSING THIRD CONNECTION
third_connection_url = [NSURL URLWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/eventostodoslist.php"];
NSURLRequest *thrid_connection_request = [NSURLRequest requestWithURL:third_connection_url];
NSURLConnection *third_connection=[[NSURLConnection alloc]initWithRequest:second_connection_request delegate:self];
}
//methods to perform the connection and population of data
-(void)connection: (NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
if(connection==first_connection){
data_for_first_connection = [[NSMutableData alloc]init];
}
else if(connection==second_connection){
data_for_second_connection = [[NSMutableData alloc]init];
}
else if(connection==third_connection){
data_for_third_connection = [[NSMutableData alloc]init];
}
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)thedata
{
if(connection==first_connection){
[data_for_first_connection appendData:thedata];
NSLog(@"CONEXION 1 AQUI");
}
else if(connection==second_connection){
[data_for_second_connection appendData:thedata];
NSLog(@"CONEXION 2 AQUI");
}
else if(connection==third_connection){
[data_for_third_connection appendData:thedata];
NSLog(@"CONEXION 3 AQUI");
}
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//if data received network indicator not visible
[UIApplication sharedApplication].networkActivityIndicatorVisible=NO;
if(connection==first_connection) {
categorias_first = [NSJSONSerialization JSONObjectWithData:data_for_first_connection options:0 error:nil];
}
else if(connection==second_connection){
categorias_second = [NSJSONSerialization JSONObjectWithData:data_for_second_connection options:0 error:nil];
}
else if(connection==third_connection){
// PROCESS TO BE DONE FOR SECOND CONNECTION
categorias_third = [NSJSONSerialization JSONObjectWithData:data_for_third_connection options:0 error:nil];
}
// Create a GMSCameraPosition that tells the map to display the
// coordinate -33.86,151.20 at zoom level 6.
GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:27.9847
longitude:-15.5953
zoom:9];
mapView_ = [GMSMapView mapWithFrame:CGRectZero camera:camera];
mapView_.myLocationEnabled = YES;
mapView_.delegate = self;
self.view = mapView_;
UISegmentedControl *mainSegment = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObjects:@"Ofertas", @"Cursos", @"Eventos", nil]];
[mainSegment setSegmentedControlStyle:UISegmentedControlStyleBar];
mainSegment.frame = CGRectMake(20,80, 280, 43);
//self.navigationItem.titleView = mainSegment;
//mainSegment.selectedSegmentIndex = nil;
[mainSegment addTarget:self action:@selector(mainSegmentControl:) forControlEvents: UIControlEventValueChanged];
[self.view addSubview:mainSegment];
}
更新了测试应用程序的代码。
我已经更新了我的代码来测试它，现在我只使用两个连接。在记录结果时，我检测到数组categoria(在first_connection处)和categoria a2(在second_connection处)是从同一个JSON文件(来自first_connection)填充的:
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = @"Geolocalización";
//carga de datos JSON
//network activity indicator showed during downloading data
[UIApplication sharedApplication].networkActivityIndicatorVisible=YES;
//URL definition where php file is hosted
//conexion1
url = [NSURL URLWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/empresastodaslist.php"];
request = [NSURLRequest requestWithURL:url];
first_connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
//conexion2
url2 = [NSURL URLWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/centrostodoslist.php"];
request2 = [NSURLRequest requestWithURL:url];
second_connection = [[NSURLConnection alloc] initWithRequest:request2 delegate:self];
}
//methods to perform the connection and population of data
-(void)connection: (NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
if ([connection isEqual:first_connection]){
NSLog(@"FIRST CONNECTION RESPONSE");
data = [[NSMutableData alloc]init];
}
if ([connection isEqual:second_connection]){
NSLog(@"SECOND CONNECTION RESPONSE");
data2 = [[NSMutableData alloc]init];
}
NSLog(@"ESTOY EN DIDRECEIVERESPONSE");
}
-(void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)thedata
{
if ([connection isEqual:first_connection]){
NSLog(@"FIRST CONNECTION RECEIVED");
[data appendData:thedata];
}
if ([connection isEqual:second_connection]){
NSLog(@"SECOND CONNECTION RECEIVED");
[data2 appendData:thedata];
}
}
-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{
//if data received network indicator not visible
[UIApplication sharedApplication].networkActivityIndicatorVisible=NO;
//array waterfalls populated via JSON from database
if ([connection isEqual:first_connection]){
categorias = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
NSLog(@"DATA1 = %@",categorias);
}
if ([connection isEqual:second_connection]){
categorias2 = [NSJSONSerialization JSONObjectWithData:data2 options:0 error:nil];
NSLog(@"DATA2 = %@",categorias2);
}
NSLog(@"NUMERO DE EMPRESAS OPCION1= %lu"
, (unsigned long)[categorias count]);
NSLog(@"NUMERO DE EMPRESAS OPCION2= %lu"
, (unsigned long)[categorias2 count]);
// Create a GMSCameraPosition that tells the map to display the
// coordinate -33.86,151.20 at zoom level 6.
GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:27.9847
longitude:-15.5953
zoom:9];
mapView_ = [GMSMapView mapWithFrame:CGRectZero camera:camera];
mapView_.myLocationEnabled = YES;
mapView_.delegate = self;
self.view = mapView_;
UISegmentedControl *mainSegment = [[UISegmentedControl alloc] initWithItems:[NSArray arrayWithObjects:@"Ofertas", @"Cursos", @"Eventos", nil]];
[mainSegment setSegmentedControlStyle:UISegmentedControlStyleBar];
mainSegment.frame = CGRectMake(20,80, 280, 43);
//self.navigationItem.titleView = mainSegment;
//mainSegment.selectedSegmentIndex = nil;
[mainSegment addTarget:self action:@selector(mainSegmentControl:) forControlEvents: UIControlEventValueChanged];
[self.view addSubview:mainSegment];
}
我看到了几个问题。首先，你的连接，firstConnection, secondConnection等，是作为局部变量创建的，所以一旦viewDidLoad超出范围，它们就会被释放。当你在委托功能中检查相等性时，它们那时会是nil。您应该为这些连接创建变量或属性。另外，你不应该使用"=="来比较对象，而应该使用isEqual:。
else if([connection isEqual:third_connection]){
正如rdelmar指出的那样，直接的问题是您没有将NSURLConnection引用保存在稍后引用的变量中。这是首先要解决的问题。
更广泛的问题更根本。您启动了三个连接，但是您的connectionDidFinishLoading似乎没有意识到它将被调用三次，每个连接调用一次。值得注意的是，该例程的后一部分，即创建地图视图和段控件，将对三个JSON下载请求中的每个请求执行一次。当然，当所有三个连接都完成时，您只打算做一次与ui相关的事情。
优雅的方法是将这些单独的网络请求包装在NSOperation对象中，并使用操作队列来管理"完成逻辑"，其中包括UI的东西。您可以使用AFNetworking实现这一点，或者将NSURLConnection封装在您自己的NSOperation子类中。然后，您可以添加这三个操作，但有一个最终完成操作，取决于其他三个下载操作的完成情况，这将更新UI。
对现有代码的一个更简单的修复是添加三个布尔变量，指示三个单独的下载是否完成。然后，您的connectionDidFinishLoading(每次对三个下载请求调用它)可以为每个请求更新相应的布尔值。然后它只会执行UI相关的东西如果这三个都完成了。
您没有为您的连接调用"start"。
1)为了保持你的代码，你需要为每个连接调用"start"，在initWithRequest之后:;
例如，[first_connection start];
2)如果你所需要的(这似乎是情况)是做一个http get和获得NSData响应，你可以简单地做NSData *jsonData = [NSData dataWithContentsOfUrl:[NSURL urlWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/empresastodaslist.php"]];
3)如果你需要它发生在一个单独的线程中，你可以在一个块中调用dataWithContentsOfUrl，像这样:
<pre>
- (void) getJsonData
{
//main thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
^{
//background thread
NSData *jsonData = [NSData dataWithContentsOfUrl:[NSURL urlWithString:@"http://mujercanariasigloxxi.appgestion.eu/app_php_files/empresastodaslist.php"]];
dispatch_async(dispatch_get_main_queue(),
^{
//main thread again
//parse json and add pins
});
});
}
</pre>
祝你好运!