注意一点：Foundation框架的类, 但凡是通过类工厂方法创建的对象都是加上autorelease了

Person.m

#import "Person.h"

@implementation Person

+ (instancetype)person
{
return [[[self alloc] init] autorelease];
}


- (instancetype)initWithAge:(int)age{
if (self = [super init]) {
    _age = age;
}

return self;
}

+ (instancetype)personWithAge:(int)age
{
/*
Person *p = [[self alloc] init];
p.age = age;
return [p autorelease];
 */
return [[[self alloc] initWithAge:age] autorelease];
}

- (void)dealloc
{
NSLog(@"%s", __func__);
[super dealloc];
}
@end

main.m

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

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

@autoreleasepool {
    /*
    Person *p = [[[Person alloc] init] autorelease];
    p.age = 10;
    NSLog(@"age = %i", p.age);
    
    Person *p1 = [[[Person alloc] init] autorelease];
    
    Person *p2 = [[[Person alloc] init] autorelease];
     
     */
    
    
    /*
    Person *p = [Person person];
    p.age = 10;
    NSLog(@"age = %i", p.age);
    
     // 注意: Foundation框架的类, 但凡是通过类工厂方法创建的对象都是autorelease的
    [[NSString alloc] init];
    [NSString string];
    
//        [NSString alloc] initWithString:<#(NSString *)#>
//        [NSString stringWithString:<#(NSString *)#>];
    */
    
    /*
//        Person *p = [[[Person alloc] initWithAge:10] autorelease];
//        NSLog(@"age = %i", p.age);
    
    Person *p = [Person personWithAge:10];
    NSLog(@"age = %i", p.age);
     */
    
}
return 0;
}