iOS 内存管理~集合对象的copy和mutableCopy

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一、集合&不可变

集合类对象是指NSArray、NSDictionary、NSSet ... 之类的对象。

NSArray* arr = @[@[ @"a",@"b" ], [@[@"c", @"d"] mutableCopy],@"AA", [NSMutableStringstringWithString:@"a"]];

NSArray *arrCy = [arrcopy];

NSMutableArray *arrMCy = [arrmutableCopy];

//! 分别打印变量的内存地址及对象地址

NSLog(@"   arr :%p  %p  [%p %p %p %p]", arr, &arr, arr[0], arr[1], arr[2], arr[3]);

NSLog(@" arrCy :%p  %p  [%p %p %p %p]", arrCy, &arrCy, arrCy[0], arrCy[1], arrCy[2], arrCy[3]);

NSLog(@"arrMCy :%p  %p  [%p %p %p %p]", arrMCy, &arrMCy, arrMCy[0], arrMCy[1], arrMCy[2], arrMCy[3]);

//! 输出

arr :0x100403430 0x7fff5fbff7a0  [0x1004012600x1004032a0 0x1000010d80x1004033a0]

arrCy :0x100403430 0x7fff5fbff798  [0x1004012600x1004032a0 0x1000010d80x1004033a0]

arrMCy :0x1004034f0 0x7fff5fbff790  [0x1004012600x1004032a0 0x1000010d80x1004033a0]

从打印结果结论:

浅拷贝 :       操作是不可变集合的copy

单层深拷贝:  操作是拷贝不可变集合的mutableCopy

集合内部的元素仍然是浅拷贝,无论该元素是否是集合是否可变

二、集合&可变

NSMutableArray* arr = [NSMutableArray arrayWithObjects:@[@"a", @"b"], [NSMutableArray arrayWithObject:@"A"],@"AA", [NSMutableString stringWithString:@"a"],nil];

NSArray* arrCy = [arr copy];

NSMutableArray* arrMCy = [arr mutableCopy];

NSLog(@"   arr :%p  %p  [%p %p %p %p]", arr, &arr, arr[0], arr[1], arr[2], arr[3]);

NSLog(@" arrCy :%p  %p  [%p %p %p %p]", arrCy, &arrCy, arrCy[0], arrCy[1], arrCy[2], arrCy[3]);

NSLog(@"arrMCy :%p  %p  [%p %p %p %p]", arrMCy, &arrMCy, arrMCy[0], arrMCy[1], arrMCy[2], arrMCy[3]);

arr :0x1005023d0 0x7fff5fbff7d0  [0x1005000d00x100502140 0x1000010b80x100502320]

arrCy :0x100502500 0x7fff5fbff7c8  [0x1005000d00x100502140 0x1000010b80x100502320]

arrMCy :0x1005025c0 0x7fff5fbff7c0  [0x1005000d00x100502140 0x1000010b80x100502320]

可以看出

可变集合的copy和mutableCopy都是单层深拷贝

集合拷贝结论

集合copymutableCopy不可变对象浅 单层深可变对象单层深 单层深 

谢谢!!!