描述方法没有被调用

Question

我创建了一个例子来学习objective-c中的一些基础知识。我有一个叫Person的类，如下所示。在main方法我打电话description方法来打印一些数据，并且据我所知，description method类似于toString在java..but description方法我创建不叫

请看看下面的代码，让我知道为什么description方法的内容没有被调用。

person.h

#import <Foundation/Foundation.h> 

@interface Person : NSObject { 
    int age; 
    int weight; 
} 

-(void) setAge:(int) age; 
-(void) setWeight: (int) weight; 

-(int) getAge; 
-(int) getWeight; 

-(NSString *) description; 

@end 

person.m

#import "Person.h" 

@implementation Person 

-(void) setAge:(int) a { 
    age = a; 
} 

-(void) setWeight:(int) w { 
    weight = w; 
} 

-(int) getAge { 
    return age; 
} 

-(int) getWeight { 
    return weight; 
} 

-(NSString *) description { 
    NSString *desc = @("my age is: %i and my weight is: %i", age, weight); 
    NSLog(@"%@", desc); 
    return desc; 
} 
@end 

主要：

#import <UIKit/UIKit.h> 
#import "AppDelegate.h" 
#import "Person.h" 

int main(int argc, char * argv[]) { 
    @autoreleasepool { 

     Person *me = [[Person alloc] init]; 

     [me setAge:20]; 
     [me setWeight:55]; 

     NSString *desc = [me description]; 
     NSLog(@"%@", desc); 

     return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class])); 
    } 
} 

Answer 1

您可能需要调用description方法，但您没有收到日志消息。问题出在你制作的NSString上。这是无效的：

NSString *desc = @("my age is: %i and my weight is: %i", age, weight); 

尝试改变这一到：

NSString *desc = [NSString stringWithFormat:@"my age is: %i and my weight is: %i", age, weight];