Objective-C description method and type method

descprition Method

Person.h

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface Person : NSObject

@property(strong, nonatomic) NSString* name;

@end

NS_ASSUME_NONNULL_END

Person.m

rewrite description Method

#import "Person.h"

@implementation Person
- (NSString *)description
{
    return [NSString stringWithFormat:@"name:%@", self.name];
}
@end

main.m

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


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Person* p1 = [Person new];
        p1.name = @"dancer";
        // One is called behind the scenes description Method 
        NSLog(@"p1:%@",p1);
    }
    return 0;
}

  Type method

Person.h

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface Person : NSObject

-(instancetype)initWithName:(NSString*)name;

+(instancetype)personWithName:(NSString*)name;
+(void)sayHello;
@end
NS_ASSUME_NONNULL_END

Person.m

#import "Person.h"
@interface Person()
@property(strong, nonatomic)NSString* name;
@end

@implementation Person
- (instancetype)initWithName:(NSString *)name{
    self = [super init];
    if(self){
        _name = name;
    }
    return self;
}

+ (instancetype)personWithName:(NSString *)name{
    Person* p = [[Person alloc]initWithName:name];
    return p;
}
+ (void)sayHello{
    // Member variables cannot be accessed in class methods 
    //_name = @"dancer";
    // If the implementation logic of a method , Don't pay attention to the difference of details , It can be designed as a type method 
    NSLog(@"Hello world");
}
@end

main.m

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


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Person* p1 = [Person personWithName:@"dancer"];
        // The feedback results are the same , You can use type methods 
        [Person sayHello];
    }
    return 0;
}