OC蜕变最后一天

[NSFileManager defaultManager]

    NSFileManager *manager = [NSFileManager defaultManager];
    // 可以判断文件
    BOOL flag = [manager fileExistsAtPath:@"/Users/MJ-Hee/Desktop/lnj.txt"];
    NSLog(@"flag = %i", flag);
    // 可以判断文件夹
    flag = [manager fileExistsAtPath:@"/Users/MJ-Hee/Desktop/未命名文件夹"];
    NSLog(@"flag = %i", flag);

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL directory = NO;
    BOOL flag = [manager fileExistsAtPath:@"/Users/MJ-Hee/Desktop/未命名文件夹" isDirectory:&directory];
    NSLog(@"flag = %i, directory = %i", flag, directory);

    NSFileManager *manager = [NSFileManager defaultManager];
    NSDictionary *dict = [manager attributesOfItemAtPath:@"/Users/MJ-Hee/Desktop/hmj.txt" error:nil];
    NSLog(@"dit = %@", dict);

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager contentsOfDirectoryAtPath:@"/Users/MJ-Hee/Desktop" error:nil];
    NSLog(@"paths = %@", paths);

    NSFileManager *manager = [NSFileManager defaultManager];
    NSArray *paths = [manager subpathsAtPath:@"/Users/LNJ/Desktop/"];
    NSLog(@"paths = %@", paths);

    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createDirectoryAtPath:@"/Users/LNJ/Desktop/test" withIntermediateDirectories:YES attributes:nil error:nil];
    NSLog(@"flag = %i", flag);

    NSString *str = @"lnj";
    //NSData : 二进制数据
    //将字符串转化成二进制数据
    NSData  *data = [str dataUsingEncoding:NSUTF8StringEncoding];
    NSFileManager *manager = [NSFileManager defaultManager];
    BOOL flag = [manager createFileAtPath:@"/Users/LNJ/Desktop/abc.txt" contents:data attributes:nil];
    NSLog(@"flag = %i", flag);

    NSMutableArray *arr = [[NSMutableArray alloc] init];

    Person *p = [[Person alloc] init];
    NSLog(@"retainCount = %lu", [p retainCount]);
    //如果将一个对象添加到一个数组/字典中,那么数组会对对象进行一次retain
    [arr addObject:p];
    NSLog(@"retainCount = %lu", [p retainCount]);
    [p release];
    NSLog(@"retainCount = %lu", [p retainCount]);
    //当数组对象释放后,会给数组中所有的对象发送一条release消息
    [arr release];

    NSMutableArray *arr = [[NSMutableArray alloc] init];
    Person *p = [[Person alloc] init];
    NSLog(@"retainCount = %lu", [p retainCount]);
    [arr addObject:p];
    NSLog(@"retainCount = %lu", [p retainCount]);
    //当数组移除一个对象之后,会给这个对象发送一条release消息
    [arr removeObject:p];
    NSLog(@"retainCount = %lu", [p retainCount]);
    [p release];
    [arr release];

@protocol NSCopying
- (id)copyWithZone:(NSZone *)zone;
@end

@protocol NSMutableCopying
- (id)mutableCopyWithZone:(NSZone *)zone;
@end

    NSString *srcStr = @"lnj";
    NSString *copyStr = [srcStr copy];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);

    NSString *srcStr = @"lnj";
    NSMutableString *copyStr = [srcStr mutableCopy];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);
    [copyStr appendString:@" cool"];
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    NSMutableString *srcStr = [NSMutableString stringWithFormat:@"lnj"];
    NSString *copyStr = [srcStr copy];
    [srcStr appendString:@" cool"];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    NSMutableString *srcStr = [NSMutableString stringWithFormat:@"lnj"];
    NSMutableString *copyStr = [srcStr mutableCopy];
    [srcStr appendString:@" cool"];
    [copyStr appendString:@" 520it"];
    NSLog(@"src = %p, copy = %p", srcStr, copyStr);
    NSLog(@"src = %@, copy = %@", srcStr, copyStr);

    @interface Person : NSObject
    //用retain,外界可以修改内部的数据,此处改为copy可以防止外界修改内部的数据
    @property (nonatomic, retain) NSString *name;
    @end

    NSMutableString *str = [NSMutableString stringWithFormat:@"lnj"];

    Person *p = [[Person alloc] init];
    p.name = str;
    // person中的属性会被修改
    [str appendString:@" cool"];
    NSLog(@"name = %@", p.name);

    Person *p = [[Person alloc] init];
    p.name = @"lnj";
    Dog *d = [[Dog alloc] init];
    d.age = 10;
    NSLog(@"retainCount = %lu", [d retainCount]); // 1
    p.pBlock = ^{
        // 会对使用到的外界对象进行一次retain
        NSLog(@"age = %d", d.age);
        NSLog(@"retainCount = %lu", [d retainCount]); // 1
    };
    [d release]; // 1
    p.pBlock();
    [p release];

-（id）copyWithZone(NSZone *)zone{

    //class用于获取一个类
   CustomMode *custom = [[[self class]  copyWithZone:zone]  init];

   Custom ->_a = [_a copyWithZone:zone];

   Custom -> _c = _c;//不是对象的 直接赋值

   Return custom;

}

-（id）copyWithZone(NSZone *)zone{

    CustomModel *custom = [super copyWithZone:zone];
    //只调用子类特有的成员变量的setter方法即可
    ….
    Return custom;
}

static 类名 *_instance = nil;
+ (instancetype)allowWithZone:(struct _NSZone *)zone
{
    //由于所有的创建方法都会调用该方法,所以只需要在该方法中控制当前对象只创建一次即可
    if (_instance == nil)
    {
        NSLog(@"创建了一个对象);
        _instance = [[super allowWithZone:zone] init;
    }
    return _instance;
    //以下代码在多线程中也能保证只执行一次
    static dispatch_once_ onceToken;
    dispatch_once(&onceToken, ^{
        _instance = [[super allowWithZone:zone] init];
    } ;)
    return _instance;
}

//copyWithZone方法用什么调用?对象
- (id)copyWithZone:(NSZone *)zone
{
    return _instance;
}

- (id)mutableCopyWithZone:(NSZone *)zone
{
    return _instance;
}

- (oneway void) release
{
    //为保证整个程序过程中只有一份实例,在这个方法中什么都不做
}

- (instancetype)retain
{
    return _instance;
}

- (NSUInteger)retainCount
{
    //注意:为了方便程序员之间沟通,一般情况下不会在单例中返回retainCount = 1,而是返回一个比较大的值
    return MAXFLOAT;
}

// 如何判断当前是ARC还是MRC?
// 可以在编译的时候判断当前是否是ARC
#if __has_feature(objc_arc)
    NSLog(@"ARC");
#else
    NSLog(@"MRC");
#endif

/*********Singleton.h**********/
// 以后就可以使用interfaceSingleton来替代后面的方法声明
#define interfaceSingleton(name)  +(instancetype)share##name

#if __has_feature(objc_arc)
// ARC
#define implementationSingleton(name)  + (instancetype)share##name { name *instance = [[self alloc] init]; return instance; } static name *_instance = nil; + (instancetype)allocWithZone:(struct _NSZone *)zone { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [[super allocWithZone:zone] init]; }); return _instance; } - (id)copyWithZone:(NSZone *)zone{ return _instance; } - (id)mutableCopyWithZone:(NSZone *)zone { return _instance; }
#else
// MRC

#define implementationSingleton(name)  + (instancetype)share##name { name *instance = [[self alloc] init]; return instance; } static name *_instance = nil; + (instancetype)allocWithZone:(struct _NSZone *)zone { static dispatch_once_t onceToken; dispatch_once(&onceToken, ^{ _instance = [[super allocWithZone:zone] init]; }); return _instance; } - (id)copyWithZone:(NSZone *)zone{ return _instance; } - (id)mutableCopyWithZone:(NSZone *)zone { return _instance; } - (oneway void)release { } - (instancetype)retain { return _instance; } - (NSUInteger)retainCount { return  MAXFLOAT; }
#endif


/********自定义类.h中********/

#import "Singleton.h"

interfaceSingleton(类名);



/********自定义类.m中********/

implementationSingleton(类名)