dispatch_group_t group = dispatch_group_create();
// 任务1
dispatch_group_enter(group);
[self getAdHotTopDataBaseRequestisScu:^(BOOL isScu) {
dispatch_group_leave(group);
}];
//任务 2
dispatch_group_enter(group);
[self getDataOfSOurcesFoucesRequestisScu:^(BOOL isScu) {
dispatch_group_leave(group);
}];
// 任务3
dispatch_group_enter(group);
[self getDataSourcesCompareRequestisScu:^(BOOL isScu) {
dispatch_group_leave(group);
}];
1,2,3任务都结束后
dispatch_group_notify(group, dispatch_get_main_queue(), ^{
});