我可以從其他 class 獲取 NSString 嗎？

Question

好吧，我有 2 個類，想從 class2 到 class1 獲取 NSString。

我哪里錯了？

class1.h

#import <Cocoa/Cocoa.h>
#import "class2.h"
@class class2;
@interface class1 : NSObject
-(IBAction)getstringfromclass2(id)sender;
@end

class1.m

#import "class1.h"
@implementation class1
-(IBAction)getstringfromclass2(id)sender {
    class2 *controller = [[class2 alloc] init];
    NSLog(@"%@", [controller getstring]);
}
@end

類2.h

#import <Cocoa/Cocoa.h>
@interface class2 : NSObject {
    NSString *astring;
}
-(NSString)getstring;
@property (readwrite,retain) NSString *astring;
@end

class2.m

#import "class2.h"
@synthesize astring;
@implementation class2
-(NSString)getstring {
    return [self astring];
}
@end

Answer 1

檢查你的一些表情。 NSString -> NSString *

#import <Cocoa/Cocoa.h>
@interface class2 : NSObject {
    NSString *astring;
}
-(NSString *)getstring;
@property (readwrite,retain) NSString *astring;
@end
class2.m

#import "class2.h"
@synthesize astring;
@implementation class2
-(NSString *)getstring {
    return [self astring];
}
@end

Answer 2

您需要返回指向NSString的指針：

-(NSString*)getstring {
    return [self astring];
}

和：

-(NSString*)getstring;