iPhone 设置 ViewController 嵌套在 NSMutableArray 中
您好，我正在尝试为嵌套在 NSMutableArray 内的视图控制器设置属性， 例如，我在这个数组中有 3 个 ViewController：
FirstViewController *firstViewController = [FirstViewController alloc];
SecondViewController *secondViewController = [SecondViewController alloc];
ThirdViewController *thirdViewController = [ThirdViewController alloc];
NSMutableArray *viewControllerClasses = [[NSMutableArray alloc] initWithObjects:
firstViewController,
secondViewController,
thirdViewController,
nil];
for (int x=0; x<[viewControllerClasses count]; x++) {
// as an example to set managedObjectContext I otherwise would set firstViewController.managedObjectContext = context;
[viewControllerClasses objectAtIndex:x].managedObjectContext = context;
}
但这会导致错误：请求成员“managedObjectContext”不是结构或联合。 “firstViewController”不应该与 [viewControllerClasses objectAtIndex:0] 相同吗？
Hello I'm trying to set attributes for a viewcontroller nested inside a NSMutableArray,
for example I have 3 ViewController inside this array:
FirstViewController *firstViewController = [FirstViewController alloc];
SecondViewController *secondViewController = [SecondViewController alloc];
ThirdViewController *thirdViewController = [ThirdViewController alloc];
NSMutableArray *viewControllerClasses = [[NSMutableArray alloc] initWithObjects:
firstViewController,
secondViewController,
thirdViewController,
nil];
for (int x=0; x<[viewControllerClasses count]; x++) {
// as an example to set managedObjectContext I otherwise would set firstViewController.managedObjectContext = context;
[viewControllerClasses objectAtIndex:x].managedObjectContext = context;
}
But this results in an error: Request for member "managedObjectContext" in something not a structure or union.
Shouldn't be "firstViewController" be the same as [viewControllerClasses objectAtIndex:0]?
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（2）
-objectAtIndex:方法返回一个id，但不能应用点语法，因为编译器无法确定 getter。无论如何，您应该只使用快速枚举（
for/in循环），并且您可以给出静态类型，以便可以使用点语法（假设 FirstViewController 和其余部分）继承自 BaseViewController）：此外，您可以恢复使用括号：（
请在
+alloc之后立即使用-init...。）The
-objectAtIndex:method returns anid, which the dot-syntax cannot be applied on because the compiler can't determine the getter.Anyway, you should just use fast enumeration (
for/inloop), and you could give a static type so the dot-syntax can be used (assuming FirstViewController and the rest inherits from BaseViewController):Also, you could revert to use brackets:
(and please
-init…immediately after+alloc.)您可以尝试转换
[viewControllerClasses objectAtIndex:x]返回一个没有managedObjectContext属性的任意NSObject，因此请尝试使用( (FirstViewController *)[viewControllerClasses objectAtIndex:x]).managementObjectContext = context;You may try casting
[viewControllerClasses objectAtIndex:x]returns an arbitaryNSObjectthat doesn't havemanagedObjectContextproperty, so try using((FirstViewController *)[viewControllerClasses objectAtIndex:x]).managedObjectContext = context;