Objective-C 错误“'XYZPerson' 没有可见的 @interface 声明选择器 'saySomething'

我对 Objective-C 确实很陌生，当我练习书本上的练习时，我真的被困在这里了。请帮助我解决这个问题，我已经思考了三个多小时可能导致此错误的原因。我还是没明白！

此致， 拉杰.

提前致谢 ！

main.m

#import <Foundation/Foundation.h>
#import "XYZPerson.h"
#import "XYZShout.h"
int main(int argc, const char * argv[])
{

    @autoreleasepool {

        //XYZPerson *some = [[XYZPerson alloc]init];

        XYZShout *some = [[XYZShout alloc]init];
        [some sayHello];



        // insert code here...
       // NSLog(@"Hello, World!");

    }
    return 0;
}

XYZPerson.h

#import <Foundation/Foundation.h>
@interface XYZPerson : NSObject

@property NSString *firstName;
@property NSString *secondName;
@property NSDate *dob;

-(void) saySomething;
-(void) sayHello;

@end

XYZPerson.m

#import "XYZPerson.h"
@implementation XYZPerson

-(void) sayHello {
    [self saySomething:@"Hello all"];
}

-(void) saySomething:(NSString *)greet {
    NSLog(@"%@", greet);
}

@end

XYZShout.h

#import "XYZPerson.h"

@interface XYZShout : XYZPerson

// -(void) saySomething;

@end

XYZShout.m

#import "XYZShout.h"

@implementation XYZShout

-(void) saySomething:(NSString *)greet {
    NSString *upperGreet = [greet uppercaseString];
    [super saySomething:upperGreet];    // this is where I get the error mentioned above
}

@end

成功了！感谢@MatthewD、@trojanfoe、@JFS 的大力帮助:)

看来您正在测试继承，所以我假设XYZShout应该是源自XYZPerson。如果是这样，请遵循@JFS 的建议并确保它确实派生：

XYZShout.h：

#import <Foundation/Foundation.h>
#import "XYZPerson.h"

@interface XYZShout : XYZPerson

- (void)saySomething:(NSString *)greet;

@end

并且还纠正了定义saySomething in XYZPerson（你错过了参数）：

XYZPerson.h：

#import <Foundation/Foundation.h>
@interface XYZPerson : NSObject

@property NSString *firstName;
@property NSString *secondName;
@property NSDate *dob;

- (void)saySomething:(NSString *)greet;
//                   ^^^^^^^^^^^^^^^^^
- (void)sayHello;

@end