xcode 在前向类中找不到属性
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Property can not be found in forward class
提问by arne somborn
I got a problem that has been bugging me for a while - especially since it doesn't make any sense to me.
我遇到了一个困扰我一段时间的问题 - 特别是因为它对我没有任何意义。
Xcode seems not to find some properties of my objects, even though they are correctly declared. Here some code:
Xcode 似乎没有找到我的对象的某些属性，即使它们被正确声明。这里有一些代码：
the .h file
.h 文件
@interface Start1ViewController : UIViewController {
NSString *updatedStatus;
NSString *updatedTime;
}
@property (retain, nonatomic) NSString *updatedTime;
@property (retain, nonatomic) NSString *updatedStatus;
and the respective synthesize in the .m
以及 .m 中的相应合成
#import "Start1ViewController.h"
@implementation Start1ViewController
@synthesize updatedStatus, updatedTime;
I want to access these properties from an object holding an instance of the class above:
我想从包含上述类的实例的对象访问这些属性：
#import <UIKit/UIKit.h>
@class Start1ViewController;
@interface PartyPickerViewController : UIViewController {
IBOutlet UIDatePicker *datePicker;
Start1ViewController *start1ViewController;
}
.m
.m
-(IBAction)buttonPressed:(id)sender{
NSDate *selected =[datePicker date];
NSDateFormatter *timeFormatter = [[NSDateFormatter alloc] init];
[timeFormatter setDateFormat:@"HH:mm"];
NSString *dateString = [timeFormatter stringFromDate:selected];
[start1ViewController setUpdatedStatus:@"Party"];
[start1ViewController setUpdatedTime:dateString];
[self.navigationController popViewControllerAnimated:YES];
}
Xcode tells me that setUpdatedStatus and setUpdatedTime don't exist..and well they don't work. I tried using start1ViewController.updatedStatus=@"Party"; instead, but this won't build at all saying "property updatedStatus not found on object of class Start1ViewController"
Xcode 告诉我 setUpdatedStatus 和 setUpdatedTime 不存在......而且它们不起作用。我尝试使用 start1ViewController.updatedStatus="Party"; 相反，但这根本不会构建，说“在类 Start1ViewController 的对象上找不到属性 updatedStatus”
I had this problem before and that time I somehow got it to work by switching between using the .-notation and using the setter methods explicitly several times, but even in that other case where it did work I still got warnings for the methods and the "property not found" when using .notation
我之前遇到过这个问题，那次我以某种方式通过在使用 .-notation 和显式使用 setter 方法之间切换多次使其工作，但即使在它确实工作的其他情况下，我仍然收到有关方法和使用 .notation 时“未找到属性”
The properties in question are simple NSStrings, so I doubt that it might be a problem that the other class doesn't know about the NSString class?
有问题的属性是简单的 NSStrings，所以我怀疑这可能是另一个类不知道 NSString 类的问题吗？
Thanks in advance for any help! =)
在此先感谢您的帮助！=)
回答by Adrian Ancuta
Did you import the Start1ViewController.hin PartyPickerViewController.m?
Because when you use in your interface @class, you just make a promise to the compiler that there is a class called Start1ViewController.
But after that you need to import Start1ViewController.hin your implementation in order to make the Start1ViewController.h, it's properties and methods visible to the other classes.
你导入Start1ViewController.h的PartyPickerViewController.m？因为当您在接口 @class 中使用时，您只需向编译器承诺有一个名为Start1ViewController. 但在那之后，您需要Start1ViewController.h在您的实现中导入，以使Start1ViewController.h, 它的属性和方法对其他类可见。
