深拷贝，浅拷贝概念
深拷贝就是把原来的数据拷贝出来存到一块新的内存中，并有一个新的指针指向新的内存，拷贝结束之后，两个对象虽然存的值是相同的，但是内存地址不一样，两个对象也互不影响，互不干涉。
浅拷贝就是拷贝数据所在内存的地址，让目标对象指针和源对象指向同一片内存空间；在 OC 里面， 使用retain 关键字进行引用计数，就是一种更加保险的浅拷贝。他既让几个指针共用同一片内存空间，又可以在release 由于计数的存在，不会轻易的销毁内存，达到更加简单使用的目的。
OC里面copy与mutable copy与赋值分别是浅拷贝还是深拷贝？
直接写个demo测试下：
@property (nonatomic, strong)NSMutableArray *suyaMArray;
@property (nonatomic, strong)NSArray *suyaIMArray;
self.suyaMArray = @[@1,@2,@3,@4,@6].mutableCopy;
NSMutableArray *suyaAssignmentMArray = self.suyaMArray;
NSMutableArray *suyaMArrayMutableCopy = self.suyaMArray.mutableCopy;
NSArray *suyaMArrayCopy = self.suyaMArray.copy;
NSLog(@"suyaMArray%p,%@",self.suyaMArray,self.suyaMArray);
[self.suyaMArray removeObject:@1];
NSLog(@"suyaMArray%p,%@",self.suyaMArray,self.suyaMArray);
NSLog(@"suyaAssignmentMArray%p,%@",suyaAssignmentMArray,suyaAssignmentMArray);
NSLog(@"suyaMArrayMutableCopy%p,%@",suyaMArrayMutableCopy,suyaMArrayMutableCopy);
NSLog(@"suyaMArrayCopy%p,%@",suyaMArrayCopy,suyaMArrayCopy);
self.suyaIMArray = @[@1,@2,@3,@4,@6].copy;
NSArray *suyaAssignmentIMArray = self.suyaIMArray;
NSArray *suyaIMArrayCopy = self.suyaIMArray.copy;
NSMutableArray *suyaIMArrayMutableCopy = self.suyaIMArray.mutableCopy;
NSLog(@"self.suyaIMArray%p,%@",self.suyaIMArray,self.suyaIMArray);
self.suyaIMArray = @[@2].copy;
NSLog(@"self.suyaIMArray%p,%@",self.suyaIMArray,self.suyaIMArray);
NSLog(@"suyaAssignmentIMArray%p,%@",suyaAssignmentIMArray,suyaAssignmentIMArray);
NSLog(@"suyaIMArrayCopy%p,%@",suyaIMArrayCopy,suyaIMArrayCopy);
NSLog(@"suyaIMArrayMutableCopy%p,%@",suyaIMArrayMutableCopy,suyaIMArrayMutableCopy);
打印结果：
suyaMArray0x6000002450a0,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.089 TestDemo[14783:876388] suyaMArray0x6000002450a0,(
2,
3,
4,
6
)
2017-09-11 17:17:52.089 TestDemo[14783:876388] suyaAssignmentMArray0x6000002450a0,(
2,
3,
4,
6
)
2017-09-11 17:17:52.089 TestDemo[14783:876388] suyaMArrayMutableCopy0x6000002451c0,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.090 TestDemo[14783:876388] suyaMArrayCopy0x6000000727c0,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.090 TestDemo[14783:876388] self.suyaIMArray0x600000072340,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.090 TestDemo[14783:876388] self.suyaIMArray0x600000019920,(
2
)
2017-09-11 17:17:52.090 TestDemo[14783:876388] suyaAssignmentIMArray0x600000072340,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.090 TestDemo[14783:876388] suyaIMArrayCopy0x600000072340,(
1,
2,
3,
4,
6
)
2017-09-11 17:17:52.091 TestDemo[14783:876388] suyaIMArrayMutableCopy0x6000002451f0,(
1,
2,
3,
4,
6
)
先看关于可变对象NSMutableArray *suyaMArray这部分。直接赋值的suyaAssignmentMArray的指针与self.suyaMArray的指针相同且值随着suyaMArray改变而改变，这是浅拷贝；mutablecopy的suyaMArrayMutableCopy的指针与self.suyaMArray的指针不同且值不随着self.suyaMArray改变而改变，这是深拷贝；copy的suyaMArrayCopy与self.suyaMArray的指针不同且值不随着self.suyaMArray改变而改变，这也是深拷贝。
再看关于非可变对象NSArray *suyaIMArray这部分。直接赋值的suyaAssignmentIMArray的指针与self.suyaIMArray的改变前的指针相同，为浅拷贝；copy的suyaIMArrayCopy的指针与self.suyaIMArray的改变前的指针相同，为浅拷贝；mutablecopy的suyaIMArrayMutableCopy的指针与self.suyaIMArray的改变前的指针不同，为深拷贝。
总结如图：
NSString、NSMutableString、NSDictionary、NSMutableDictionary一样适用。表中的对象类型NSMutableArray可以改成可变对象，NSArray可以改为非可变对象。
思考：
如果修饰属性都改为copy那么赋值之后的拷贝类型是什么呢？
