时不时会有点迷惑属性修饰符retain、strong、copy三者之间的区别，还是把测试过程记录下来好一点！
2、给retain、strong、copy修饰的字符串属性赋值指针变化测试例子
3、字符串调用copy、mutableCopy方法给字符串赋值指针变化例子
一、属性修饰符retain、strong、copy修饰字符串测试
先看代码，创建一个Person类，定义属性
#import <Foundation/Foundation.h> @interface Person : NSObject @property (nonatomic, retain) NSString *strRetain; @property (nonatomic, strong) NSString *strStrong; @property (nonatomic, copy) NSString *strCopy; @property (nonatomic, retain) NSMutableString *strMutableRetain; @property (nonatomic, strong) NSMutableString *strMutableStrong; @property (nonatomic, copy) NSMutableString *strMutableCopy; @end
测试代码：
1 Person *per = [[Person alloc] init]; 2 NSString *name = @"原XM"; 3 [per setStrRetain:name]; 4 [per setStrStrong:name]; 5 per.strCopy = name; 6 7 NSMutableString *name2 = [[NSMutableString alloc] initWithString:@"原XM2"]; 8 per.strMutableRetain = name2; 9 per.strMutableStrong = name2; 10 per.strMutableCopy = name2; 11 12 NSLog(@"------ 改变之前打印 ------"); 13 NSLog(@"per.strRetain: %@, ", per.strRetain); 14 NSLog(@"per.strStrong: %@", per.strStrong); 15 NSLog(@"per.strCopy: %@", per.strCopy); 16 NSLog(@"per.strMutableRetain: %@", per.strMutableRetain); 17 NSLog(@"per.strMutableStrong: %@", per.strMutableStrong); 18 NSLog(@"per.strMutableCopy: %@", per.strMutableCopy); 19 20 name = @"新XM"; 21 [name2 appendString:@"新XM2"]; 22 23 NSLog(@"------- 改变之后打印 -------"); 24 NSLog(@"per.strRetain: %@", per.strRetain); 25 NSLog(@"per.strStrong: %@", per.strStrong); 26 NSLog(@"per.strCopy: %@", per.strCopy); 27 NSLog(@"per.strMutableRetain: %@", per.strMutableRetain); 28 NSLog(@"per.strMutableStrong: %@", per.strMutableStrong); 29 NSLog(@"per.strMutableCopy: %@", per.strMutableCopy);
打印日志：
------ 改变之前打印 ------ per.strRetain: 原XM, per.strStrong: 原XM per.strCopy: 原XM per.strMutableRetain: 原XM2 per.strMutableStrong: 原XM2 per.strMutableCopy: 原XM2 ------- 改变之后打印 ------- per.strRetain: 原XM per.strStrong: 原XM per.strCopy: 原XM per.strMutableRetain: 原XM2新XM2 per.strMutableStrong: 原XM2新XM2 per.strMutableCopy: 原XM2
结论：
1、对于不可变对象来说：retain、strong、copy三者的作用是一样的，即当引用的原对象值改变后，其他引用该对象的属性值不会受影响，还是保持原来的值；
2、对于可变对象来说：retain、strong和copy的作用就有区别了，使用retain、strong修饰的属性，当引用的原对象值改变后，其他引用该对象的属性值会一起跟着变化，而copy修饰的属性的值还是保持原样。copy的作用主要也是体现在这里： 让属性值不会随着原引用对象的值改变而改变；
3、retain和strong的区别：作用是一样的，只是写法上的区别。在非arc机制时，是用retain关键字修饰；在arc机制后，一般都用strong关键字来代替retain了
4、根本原因是：给字符串属性赋值不可变字符串，retain、strong、copy修饰的可变和不可变字符串属性都是指针拷贝；
给字符串属性赋值可变字符串，retain、strong修饰的可变和不可变字符串属性是指针拷贝，而copy修饰的可变和不可变字符串属性都是内容拷贝。
(说明一下：第一种情况，给字符串属性赋值不可变字符串，虽然retain、strong、copy修饰的属性都是指针拷贝，但是因为源数据是不可变字符串，导致源数据值改变后，相应的就是另外一个指针地址了，但是这些属性还是原来的指针，所以值也是原来的值不会改变；
第二种情况，给字符串属性赋值可变字符串，retain、strong修饰的属性是指针拷贝，所以源可变字符串值改变后，指针没变，则retain、strong修饰的属性指针与源字符串一样，所以值也跟着变化；而copy修饰的字符串属性是内容拷贝，源字符串的值改变和属性已经没有关系了，因而不会引起属性值改变。
所以，我们如果从效果来看的话，想要源字符串值的改变不引起属性字符串值的改变，只有当源字符串是可变字符串时，属性才需要用copy修饰，其他情况使用strong、retain修饰效果是一样的，虽然是指针拷贝，但是源字符串值的改变不会引起属性字符串值的改变。当然我们还是要理解他们的区别才是王道。所以一般字符串属性都是用copy来修饰，靠谱的用法！
)
指针变化见如下代码
------ 再次打印，这次把指针的变化都打印出来，一目了然，彻底明白 ------
NSString *str1 = @"oneone壹亿一"; Person *obj = [[Person alloc] init]; obj.strStrong = str1; //指针拷贝 obj.strRetain = str1; //指针拷贝 obj.strCopy = str1; //指针拷贝 obj.strMutableStrong = str1; //指针拷贝 obj.strMutableRetain = str1; //指针拷贝 obj.strMutableCopy = str1; //指针拷贝 NSLog(@"指针1：%p, %p, %p, %p, %p, %p, %p", str1, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值1：%@, %@, %@, %@, %@, %@, %@", str1, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针1：0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30 值1：oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一 */ str1 = @"twotwo我"; NSLog(@"指针2：%p, %p, %p, %p, %p, %p, %p", str1, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值2：%@, %@, %@, %@, %@, %@, %@", str1, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针2：0x10c861e90, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30, 0x10c861e30 值2：twotwo我, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一, oneone壹亿一 */ NSString *str2 = [[NSString alloc] initWithFormat:@"three哈%d", 8]; obj.strStrong = str2; //指针拷贝 obj.strRetain = str2; //指针拷贝 obj.strCopy = str2; //指针拷贝 obj.strMutableStrong = str2; //指针拷贝 obj.strMutableRetain = str2; //指针拷贝 obj.strMutableCopy = str2; //指针拷贝 NSLog(@"指针3：%p, %p, %p, %p, %p, %p, %p", str2, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值3：%@, %@, %@, %@, %@, %@, %@", str2, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针3：0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650 值3：three哈8, three哈8, three哈8, three哈8, three哈8, three哈8, three哈8 */ str2 = @"four啊"; NSLog(@"指针4：%p, %p, %p, %p, %p, %p, %p", str2, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值4：%@, %@, %@, %@, %@, %@, %@", str2, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针4：0x10c861f50, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650, 0x7fb9f9e04650 值4：four啊, three哈8, three哈8, three哈8, three哈8, three哈8, three哈8 */ NSLog(@" ---- start NSMutableString -------"); NSMutableString *str3 = [[NSMutableString alloc] initWithString:@"five神"]; obj.strStrong = str3; //指针拷贝 obj.strRetain = str3; //指针拷贝 obj.strCopy = str3; //内容拷贝 obj.strMutableStrong = str3; //指针拷贝 obj.strMutableRetain = str3; //指针拷贝 obj.strMutableCopy = str3; //内容拷贝 /* .语法和setter方法设置值的效果是一样的 [obj setStrStrong: str3]; [obj setStrRetain: str3]; [obj setStrCopy: str3]; [obj setStrMutableStrong: str3]; [obj setStrMutableRetain: str3]; [obj setStrMutableCopy: str3]; */ NSLog(@"指针5：%p, %p, %p, %p, %p, %p, %p", str3, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值5：%@, %@, %@, %@, %@, %@, %@", str3, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针5：0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d9b6c0, 0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d0b930 值5：five神, five神, five神, five神, five神, five神, five神 */ [str3 appendString:@"明天"]; NSLog(@"指针6：%p, %p, %p, %p, %p, %p, %p", str3, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); NSLog(@"值6：%@, %@, %@, %@, %@, %@, %@", str3, obj.strStrong, obj.strRetain, obj.strCopy, obj.strMutableStrong, obj.strMutableRetain, obj.strMutableCopy); /* 指针6：0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d9b6c0, 0x7fb9f9d9b920, 0x7fb9f9d9b920, 0x7fb9f9d0b930 值6：five神明天, five神明天, five神明天, five神, five神明天, five神明天, five神 */
再次描述下结论：
给字符串属性赋值不可变字符串，retain、strong、copy修饰的可变和不可变字符串属性都是指针拷贝；
给字符串属性赋值可变字符串，retain、strong修饰的可变和不可变字符串属性是指针拷贝，而copy修饰的可变和不可变字符串属性都是内容拷贝。
关键变化，截图标识一下：
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二、字符串调用copy、mutableCopy方法给字符串赋值
看看字符串调用copy和mutableCopy方法给字符串赋值，还有给属性修饰符修饰的字符串属性赋值指针变化
先看代码1：
//不可变字符串 NSString *str = @"aa啊"; NSString *str1 = [str copy]; //指针拷贝 NSString *str2 = [str mutableCopy]; //内容拷贝 NSMutableString *str3 = [str copy]; //指针拷贝 NSMutableString *str4 = [str mutableCopy]; //内容拷贝 NSLog(@"指针1：%p, %p, %p, %p, %p", str, str1, str2, str3, str4); /* 指针1：0x1041093f0, 0x1041093f0, 0x7f951840b6e0, 0x1041093f0, 0x7f951840dfe0 */ //可变字符串 NSMutableString *str5 = [NSMutableString stringWithString:@"bb吧"]; str1 = [str5 copy]; //内容拷贝 str2 = [str5 mutableCopy]; //内容拷贝 str3 = [str5 copy]; //内容拷贝 str4 = [str5 mutableCopy]; //内容拷贝 NSLog(@"指针2：%p, %p, %p, %p, %p", str5, str1, str2, str3, str4); NSLog(@"值2：%@, %@, %@, %@, %@", str5, str1, str2, str3, str4); /* 指针2：0x7f9518410af0, 0x7f9518435840, 0x7f9518416390, 0x7f9518403a00, 0x7f951840b6e0 值2：bb吧, bb吧, bb吧, bb吧, bb吧 */ [str5 appendString:@"大大"]; NSLog(@"指针3：%p, %p, %p, %p, %p", str5, str1, str2, str3, str4); NSLog(@"值3：%@, %@, %@, %@, %@", str5, str1, str2, str3, str4); /* 指针3：0x7f9518410af0, 0x7f9518435840, 0x7f9518416390, 0x7f9518403a00, 0x7f951840b6e0 值3：bb吧大大, bb吧, bb吧, bb吧, bb吧 */
结论：1）、不可变字符串使用copy方法赋值给其他可变或不可变字符串，都是指针拷贝；
2）、不可变字符串使用mutableCopy方法赋值给可变或不可变字符串，和可变字符串使用copy方法或者mutableCopy方法赋值给其他可变或不可变字符串，都是内容拷贝
再看代码2：
Person *obj = [[Person alloc] init]; NSString *str = @"y壹"; //不可变字符串调用copy方法，全部指针拷贝 obj.strStrong = [str copy]; obj.strCopy = [str copy]; obj.strMutableStrong = [str copy]; obj.strMutableCopy = [str copy]; NSLog(@"指针1：%p, %p, %p, %p, %p", str, obj.strStrong, obj.strCopy, obj.strMutableStrong, obj.strMutableCopy); //指针1：0x101be34f0, 0x101be34f0, 0x101be34f0, 0x101be34f0, 0x101be34f0 //不可变字符串调用mutableCopy方法，全部内容拷贝 str = @"e二"; obj.strStrong = [str mutableCopy]; obj.strCopy = [str mutableCopy]; obj.strMutableStrong = [str mutableCopy]; obj.strMutableCopy = [str mutableCopy]; NSLog(@"指针2：%p, %p, %p, %p, %p", str, obj.strStrong, obj.strCopy, obj.strMutableStrong, obj.strMutableCopy); //指针2：0x101be3510, 0x7ff939498790, 0x7ff9394a2020, 0x7ff9394970c0, 0x7ff939405d40 //可变字符串调用copy方法，全部内容拷贝 NSMutableString *str2 = [NSMutableString stringWithString:@"h叁"]; obj.strStrong = [str2 copy]; obj.strCopy = [str2 copy]; obj.strMutableStrong = [str2 copy]; obj.strMutableCopy = [str2 copy]; NSLog(@"指针3：%p, %p, %p, %p, %p", str2, obj.strStrong, obj.strCopy, obj.strMutableStrong, obj.strMutableCopy); //指针3：0x7ff93951f540, 0x7ff93954a100, 0x7ff9395288c0, 0x7ff939516ca0, 0x7ff939548db0 //可变字符串调用mutableCopy方法，全部内容拷贝 [str2 appendString:@"叁2"]; obj.strStrong = [str2 mutableCopy]; obj.strCopy = [str2 mutableCopy]; obj.strMutableStrong = [str2 mutableCopy]; obj.strMutableCopy = [str2 mutableCopy]; NSLog(@"指针4：%p, %p, %p, %p, %p", str2, obj.strStrong, obj.strCopy, obj.strMutableStrong, obj.strMutableCopy); //指针4：0x7ff93951f540, 0x7ff93951f320, 0x7ff93954a100, 0x7ff9395627b0, 0x7ff939516ca0
结论：1）、不可变字符串调用copy给strong, copy修饰的属性赋值，都是指针拷贝；
2）、不可变字符串调用mutableCopy, 和可变字符串调用copy，和可变字符串调用mutableCopy方法给strong、copy修饰的属性赋值，都是内容拷贝
所以说属性修饰符copy不一定代表着深拷贝，碰上数据源为不可变数据则是浅拷贝（指针拷贝），碰上数据源是可变数据则是深拷贝（内容拷贝）；
NSObject的方法copy也不一定代表着浅拷贝，碰上数据源为不可变数据则是浅拷贝，碰上数据源是可变数据则是深拷贝；
NSObject的方法mutableCopy不管数据源是不可变还是可变，都是深拷贝；
这以上几个结论适用字符串，也适用下面的数组测试！
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三、给修饰符strong、copy修饰的数组赋值测试
先创建一个有数组属性的模型类TestArr :
@interface TestArr : NSObject //测试数组的copy和strong属性 @property (nonatomic, strong) NSArray *arrStrong; @property (nonatomic, copy) NSArray *arrCopy; @property (nonatomic, strong) NSMutableArray *arrMutableStrong; @property (nonatomic, copy) NSMutableArray *arrMutableCopy; @end
1、数组直接赋值给修饰符strong、copy修饰的属性
NSArray *arr1 = [NSArray arrayWithObjects:@"twotwo2", nil]; TestArr *arrObj = [[TestArr alloc] init]; // arrObj.arrStrong = arr1; //指针拷贝 // arrObj.arrCopy = arr1; //指针拷贝 // arrObj.arrMutableStrong = arr1; //指针拷贝 // arrObj.arrMutableCopy = arr1; //指针拷贝 //.语法和setter方法设置值效果一样 [arrObj setArrStrong:arr1]; [arrObj setArrCopy:arr1]; [arrObj setArrMutableStrong:arr1]; [arrObj setArrMutableCopy:arr1]; NSLog(@"指针9：%p, %p, %p, %p, %p", arr1, arrObj.arrStrong, arrObj.arrCopy, arrObj.arrMutableStrong, arrObj.arrMutableCopy); NSLog(@"值9：%@, %@, %@, %@, %@", arr1[0], arrObj.arrStrong[0], arrObj.arrCopy[0], arrObj.arrMutableStrong[0], arrObj.arrMutableCopy[0]); /* 指针9：0x7fd8e8e04870, 0x7fd8e8e04870, 0x7fd8e8e04870, 0x7fd8e8e04870, 0x7fd8e8e04870 值9：twotwo2, twotwo2, twotwo2, twotwo2, twotwo2 */ arr1 = @[@"TEST哈"]; NSLog(@"指针10：%p, %p, %p, %p, %p", arr1, arrObj.arrStrong, arrObj.arrCopy, arrObj.arrMutableStrong, arrObj.arrMutableCopy); NSLog(@"值10：%@, %@, %@, %@, %@", arr1[0], arrObj.arrStrong[0], arrObj.arrCopy[0], arrObj.arrMutableStrong[0], arrObj.arrMutableCopy[0]); /* 指针10：0x7fd8e8e0cda0, 0x7fd8e8e04870, 0x7fd8e8e04870, 0x7fd8e8e04870, 0x7fd8e8e04870 值10：TEST哈, twotwo2, twotwo2, twotwo2, twotwo2 */ NSMutableArray *arr6 = [NSMutableArray arrayWithObjects:@"风清扬", nil]; //赋值可变数组 arrObj.arrStrong = arr6; //指针拷贝 arrObj.arrCopy = arr6; //内容拷贝 arrObj.arrMutableStrong = arr6; //指针拷贝 arrObj.arrMutableCopy = arr6; //内容拷贝 NSLog(@"指针11：%p, %p, %p, %p, %p", arr6, arrObj.arrStrong, arrObj.arrCopy, arrObj.arrMutableStrong, arrObj.arrMutableCopy); NSLog(@"值11：%@, %@, %@, %@, %@", arr6[0], arrObj.arrStrong[0], arrObj.arrCopy[0], arrObj.arrMutableStrong[0], arrObj.arrMutableCopy[0]); /* 指针11：0x7fd8e8f1cce0, 0x7fd8e8f1cce0, 0x7fd8e8c14480, 0x7fd8e8f1cce0, 0x7fd8e8c14f00 值11：风清扬, 风清扬, 风清扬, 风清扬, 风清扬 */ arr6[0] = @"哈宝"; NSLog(@"指针12：%p, %p, %p, %p, %p", arr6, arrObj.arrStrong, arrObj.arrCopy, arrObj.arrMutableStrong, arrObj.arrMutableCopy); NSLog(@"值12：%@, %@, %@, %@, %@", arr6[0], arrObj.arrStrong[0], arrObj.arrCopy[0], arrObj.arrMutableStrong[0], arrObj.arrMutableCopy[0]); /* 指针12：0x7fd8e8f1cce0, 0x7fd8e8f1cce0, 0x7fd8e8c14480, 0x7fd8e8f1cce0, 0x7fd8e8c14f00 值12：哈宝, 哈宝, 风清扬, 哈宝, 风清扬 */
结论：1)、不可变数组直接赋值给strong、copy修饰的数组属性，都是指针拷贝
2)、可变数组直接赋值给strong修饰的可变或不可变数组属性，都是指针拷贝；赋值给copy修饰的可变或不可变数组属性，都是内容拷贝
效果和字符串属性的效果是一样的！
2、数组调用copy、mutableCopy方法给数组赋值
NSArray *arr1 = [[NSArray alloc] initWithObjects:@"onone", nil]; NSArray *arr2 = [[NSArray alloc] initWithObjects:@"onone", nil]; NSArray *arr3 = [[NSArray alloc] initWithObjects:@"onone", nil]; NSMutableArray *arr4 = [[NSMutableArray alloc] initWithObjects:@"onone", nil]; NSMutableArray *arr5 = [[NSMutableArray alloc] initWithObjects:@"onone", nil]; NSLog(@"指针0：%p, %p, %p, %p, %p", arr1, arr2, arr3, arr4, arr5); /* 指针0：0x7fd8e8db25b0, 0x7fd8e8d06540, 0x7fd8e8d132b0, 0x7fd8e8db1bc0, 0x7fd8e8db2620 */ arr2 = [arr1 copy]; //指针拷贝 arr3 = [arr1 mutableCopy]; //内容拷贝 arr4 = [arr1 copy]; //指针拷贝 arr5 = [arr1 mutableCopy]; //内容拷贝 NSLog(@"指针1：%p, %p, %p, %p, %p", arr1, arr2, arr3, arr4, arr5); NSLog(@"值1：%@, %@, %@, %@, %@", arr1[0], arr2[0], arr3[0], arr4[0], arr5[0]); /* 指针1：0x7fd8e8db25b0, 0x7fd8e8db25b0, 0x7fd8e8daff70, 0x7fd8e8db25b0, 0x7fd8e8db1bc0 值1：onone, onone, onone, onone, onone */ arr1 = @[@"twotwo"]; NSLog(@"指针2：%p, %p, %p, %p, %p", arr1, arr2, arr3, arr4, arr5); NSLog(@"值2：%@, %@, %@, %@, %@", arr1[0], arr2[0], arr3[0], arr4[0], arr5[0]); /* 指针2：0x7fd8e8f036e0, 0x7fd8e8db25b0, 0x7fd8e8daff70, 0x7fd8e8db25b0, 0x7fd8e8db1bc0 值2：twotwo, onone, onone, onone, onone */ NSMutableArray *arr6 = [NSMutableArray arrayWithObjects:@"three", nil]; arr2 = [arr6 copy]; //内容拷贝 arr3 = [arr6 mutableCopy]; //内容拷贝 arr4 = [arr6 copy]; //内容拷贝 arr5 = [arr6 mutableCopy]; //内容拷贝 NSLog(@"指针3：%p, %p, %p, %p, %p", arr6, arr2, arr3, arr4, arr5); NSLog(@"值3：%@, %@, %@, %@, %@", arr6[0], arr2[0], arr3[0], arr4[0], arr5[0]); /* 指针3：0x7fd8e8f1cce0, 0x7fd8e8f06d90, 0x7fd8e8f0c7c0, 0x7fd8e8f0c7f0, 0x7fd8e8f03150 值3：three, three, three, three, three */ arr6[0] = @"大侠"; NSLog(@"指针4：%p, %p, %p, %p, %p", arr6, arr2, arr3, arr4, arr5); NSLog(@"值4：%@, %@, %@, %@, %@", arr6[0], arr2[0], arr3[0], arr4[0], arr5[0]); /* 指针4：0x7fd8e8f1cce0, 0x7fd8e8f06d90, 0x7fd8e8f0c7c0, 0x7fd8e8f0c7f0, 0x7fd8e8f03150 值4：大侠, three, three, three, three */
结论：1)、不可变数组调用copy赋值给可变数组或不可变数组都是指针拷贝；不可变数组调用mutableCopy赋值给可变数组或不可变数组都是内容拷贝
2)、可变数组调用copy或mutableCopy赋值给可变数组或不可变数组，都是内容拷贝
效果和字符串也是一样！
3、数组调用copy、mutableCopy方法给数组属性赋值
TestArr *obj = [[TestArr alloc] init]; NSArray *arr = [NSArray arrayWithObjects:@"one哦", nil]; //都是指针拷贝 obj.arrStrong = [arr copy]; obj.arrCopy = [arr copy]; obj.arrMutableStrong = [arr copy]; obj.arrMutableCopy = [arr copy]; NSLog(@"指针1：%p, %p, %p, %p, %p", arr, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值1：%@, %@, %@, %@, %@", arr[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 指针1：0x7fbf18c2a2b0, 0x7fbf18c2a2b0, 0x7fbf18c2a2b0, 0x7fbf18c2a2b0, 0x7fbf18c2a2b0 值1：one哦, one哦, one哦, one哦, one哦 */ //都是内容拷贝 arr = [NSArray arrayWithObjects:@"two他", nil]; obj.arrStrong = [arr mutableCopy]; obj.arrCopy = [arr mutableCopy]; obj.arrMutableStrong = [arr mutableCopy]; obj.arrMutableCopy = [arr mutableCopy]; NSLog(@"指针2：%p, %p, %p, %p, %p", arr, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值2：%@, %@, %@, %@, %@", arr[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 指针2：0x7fbf18f0ec40, 0x7fbf18d09e80, 0x7fbf18d36540, 0x7fbf18d09eb0, 0x7fbf18d014b0 值2：two他, two他, two他, two他, two他 */ //可变数组 //都是内容拷贝 NSMutableArray *arr2 = [NSMutableArray arrayWithObjects:@"th叁", nil]; obj.arrStrong = [arr2 copy]; obj.arrCopy = [arr2 copy]; obj.arrMutableStrong = [arr2 copy]; obj.arrMutableCopy = [arr2 copy]; NSLog(@"指针3：%p, %p, %p, %p, %p", arr2, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值3：%@, %@, %@, %@, %@", arr2[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 指针3：0x7fbf18f6c420, 0x7fbf18f693a0, 0x7fbf18f00500, 0x7fbf18f63c60, 0x7fbf18f01660 值3：th叁, th叁, th叁, th叁, th叁 */ arr2[0] = @"司ss"; NSLog(@"指针3_2：%p, %p, %p, %p, %p", arr2, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值3_2：%@, %@, %@, %@, %@", arr2[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 值3_2：司ss, th叁, th叁, th叁, th叁 */ //都是内容拷贝 obj.arrStrong = [arr2 mutableCopy]; obj.arrCopy = [arr2 mutableCopy]; obj.arrMutableStrong = [arr2 mutableCopy]; obj.arrMutableCopy = [arr2 mutableCopy]; NSLog(@"指针4：%p, %p, %p, %p, %p", arr2, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值4：%@, %@, %@, %@, %@", arr2[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 指针4：0x7fbf18f6c420, 0x7fbf18f620e0, 0x7fbf18f693a0, 0x7fbf18f6c9a0, 0x7fbf18d014b0 值4：司ss, 司ss, 司ss, 司ss, 司ss */ arr2[0]=@"Ni打野"; NSLog(@"指针5：%p, %p, %p, %p, %p", arr2, obj.arrStrong, obj.arrCopy, obj.arrMutableStrong, obj.arrMutableCopy); NSLog(@"值5：%@, %@, %@, %@, %@", arr2[0], obj.arrStrong[0], obj.arrCopy[0], obj.arrMutableStrong[0], obj.arrMutableCopy[0]); /* 值5：Ni打野, 司ss, 司ss, 司ss, 司ss */
结论：1）、不可变数组调用copy给strong、copy修饰的数组属性赋值，都是指针拷贝；
2）、 不可变数组调用mutableCopy, 和可变数组调用copy, 和可变数组调用mutableCopy方法给strong、copy修饰的数组属性赋值，都是内容拷贝
和字符串效果也是一样