Question

当我运行此代码时，控制台中没有任何内容。 print方法应显示NSLog()的内容，但不显示。这是一个单一的视图应用程序。

Person.h：

#import <Foundation/Foundation.h>

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

-(void) print;
-(void) myAge: (int) theAge;
-(void) myWeight: (int) theWeight;

@end

Person.m：

#import "Person.h"

@implementation Person

-(void) print {
    NSLog(@"My Age is %i and my weight is %i", age, weight);
}
-(void) myAge: (int) theAge {
    age = theAge;
}
-(void) myWeight: (int) theWeight {
    weight = theWeight;
}

@end

的main.m：

#import <UIKit/UIKit.h>

#import "AppDelegate.h"
#import "Person.h"

int main(int argc, char * argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }

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

    [Connor myAge: 20];
    [Connor myWeight:210];
    [Connor print];

}

Answer 1

对UIApplicationMain的调用永远不会返回，因此之后的代码永远不会运行。

在调用UIApplicationMain之前将代码移至。

为什么不使用age和weight的属性？

Person.h：

#import <Foundation/Foundation.h>

@interface Person : NSObject

@property (nonatomic, assign) int age;
@property (nonatomic, assign) int weight;

-(void) print;

@end

Person.m：

#import "Person.h"

@implementation Person

- (void) print {
    NSLog(@"My Age is %i and my weight is %i", self.age, self.weight);
}

@end

的main.m

#import <UIKit/UIKit.h>

#import "AppDelegate.h"
#import "Person.h"

int main(int argc, char * argv[])
{
    @autoreleasepool {
        Person *connor = [[Person alloc] init];

        connor.age = 20;
        connor.weight = 210;
        [connor print];

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

当我调用调用NSLog的方法时，控制台不显示输出

1 个答案: