iOS多个网络请求问题
开发中，有时候一个页面需要多个网络请求之后才能更新ui，这时候我们可以用嵌套请求方法，但是如果网络请求比较多，那么嵌套方法肯定不行了，太麻烦对吧，这时候不放用一下gcd的信号量
// 创建组
[MBProgressHUD showMessage:@"加载中..."];
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 创建信号量
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
NSString *strurl=[HSTools Joint:URL_GUBRI];
NSMutableDictionary *parameters=[NSMutableDictionary dictionary];
parameters[@"region_id"]=self.region_id;
[JSCHttpTool GET:strurl parameters:parameters success:^(id responseObject) {
NSLog(@"网络一请求成功");
if ([responseObject[@"code"] integerValue] == 1){
[self.unitArray removeAllObjects];
for (NSDictionary *unitsdict in responseObject[@"units"]) {
UnitModel *model=[[UnitModel alloc] init];
model.address=unitsdict[@"address"];
model.contact_number=unitsdict[@"contact_number"];
[self.unitArray addObject:model];
}
// 如果请求成功，发送信号量
dispatch_semaphore_signal(semaphore);
}
} failure:^(NSError *error) {
NSLog(@"网络一请求失败");
[MBProgressHUD hideHUD];
//dispatch_semaphore_signal(semaphore);
}];
// 在网络请求任务成功之前，信号量等待中
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
});
dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 创建信号量
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
NSString *strurl=[HSTools Joint:URL_GUBRI];
NSMutableDictionary *parameters=[NSMutableDictionary dictionary];
parameters[@"region_id"]=self.region_id;
[JSCHttpTool GET:strurl parameters:parameters success:^(id responseObject) {
NSLog(@"网络二请求成功");
if ([responseObject[@"code"] integerValue] == 1){
[self.otherunitArray removeAllObjects];
for (NSDictionary *unitsdict in responseObject[@"units"]) {
UnitModel *model=[[UnitModel alloc] init];
model.address=unitsdict[@"address"];
model.contact_number=unitsdict[@"contact_number"];
[self.otherunitArray addObject:model];
}
// 如果请求成功，发送信号量
dispatch_semaphore_signal(semaphore);
}
} failure:^(NSError *error) {
NSLog(@"网络二请求失败");
[MBProgressHUD hideHUD];
// dispatch_semaphore_signal(semaphore);
}];
// 在网络请求任务成功之前，信号量等待中
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
});
dispatch_group_notify(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
[MBProgressHUD hideHUD];
NSLog(@"完成了网络请求，并且都成功。");
NSLog(@"self.unitArray.count--%lu",(unsigned long)self.unitArray.count);
NSLog(@"self.otherunitArray.count--%lu",(unsigned long)self.otherunitArray.count);
});代码中，我在每个failure里面都写了一行注释掉的// dispatch_semaphore_signal(semaphore);
是因为，如果有时候我们需要不论请求成功还是失败，都走dispatch_group_notify方法的话，就可以打开此处的注释。在这里我是需要两个请求全部成功之后才允许走dispatch_group_notify方法的。
补充：经测试dispatch_group_notify里面更新ui的方法十分的卡，具体为什么，请大神评论告知
解决方法：已经找到解决方法，多个网络请求结束之后我们需要回到主线程刷新ui界面。
以下是更改过后的代码
// 创建组
[MBProgressHUD showMessage:@"加载中..."];
dispatch_group_t group = dispatch_group_create();
dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 创建信号量
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
NSString *strurl=[HSTools Joint:URL_GUBRI];
NSMutableDictionary *parameters=[NSMutableDictionary dictionary];
parameters[@"region_id"]=self.region_id;
[JSCHttpTool GET:strurl parameters:parameters success:^(id responseObject) {
NSLog(@"网络一请求成功");
if ([responseObject[@"code"] integerValue] == 1){
[self.unitArray removeAllObjects];
for (NSDictionary *unitsdict in responseObject[@"units"]) {
UnitModel *model=[[UnitModel alloc] init];
model.address=unitsdict[@"address"];
model.contact_number=unitsdict[@"contact_number"];
[self.unitArray addObject:model];
}
// 如果请求成功，发送信号量
dispatch_semaphore_signal(semaphore);
}
} failure:^(NSError *error) {
NSLog(@"网络一请求失败");
[MBProgressHUD hideHUD];
//dispatch_semaphore_signal(semaphore);
}];
// 在网络请求任务成功之前，信号量等待中
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
});
dispatch_group_async(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// 创建信号量
dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
NSString *strurl=[HSTools Joint:URL_GUBRI];
NSMutableDictionary *parameters=[NSMutableDictionary dictionary];
parameters[@"region_id"]=self.region_id;
[JSCHttpTool GET:strurl parameters:parameters success:^(id responseObject) {
NSLog(@"网络二请求成功");
if ([responseObject[@"code"] integerValue] == 1){
[self.otherunitArray removeAllObjects];
for (NSDictionary *unitsdict in responseObject[@"units"]) {
UnitModel *model=[[UnitModel alloc] init];
model.address=unitsdict[@"address"];
model.contact_number=unitsdict[@"contact_number"];
[self.otherunitArray addObject:model];
}
// 如果请求成功，发送信号量
dispatch_semaphore_signal(semaphore);
}
} failure:^(NSError *error) {
NSLog(@"网络二请求失败");
[MBProgressHUD hideHUD];
// dispatch_semaphore_signal(semaphore);
}];
// 在网络请求任务成功之前，信号量等待中
dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
});
dispatch_group_notify(group, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
dispatch_async(dispatch_get_main_queue(), ^{
[MBProgressHUD hideHUD];
NSLog(@"完成了网络请求，并且都成功。");
NSLog(@"self.unitArray.count--%lu",(unsigned long)self.unitArray.count);
NSLog(@"self.otherunitArray.count--%lu",(unsigned long)self.otherunitArray.count);
});
// 也可以加判断语句
// if (判断语句) {
// // 返回主线程进行界面上的修改
// dispatch_async(dispatch_get_main_queue(), ^{
// 更新ui
// });
// }else{
// dispatch_async(dispatch_get_main_queue(), ^{
// 更新ui
// });
// }
});