iOS NSAarray的initWithArray:copyItems:方法

数组的深拷贝与浅拷贝：

 - initWithArray:copyItems:

  Initializes a newly allocated array using anArray as the source of data objects for the array

 - (instancetype)initWithArray:(NSArray *)array  copyItems:(BOOL)flag

If flag == YES, each object in array receives a copyWithZone: message to create a copy of the object—objects must conform to the NSCopying protocol. In a managed memory environment, this is instead of the retain message the object would otherwise receive. The object copy is then added to the returned array.

If flag == NO, then in a managed memory environment each object in array simply receives a retain message when it is added to the returned array.

根据苹果开发者文档说明：只有遵守copy协议的数组元素对象才能进行深拷贝，将对象的副本添加到新的数组里面。如果数组元素对象不遵守copy协议，则会进行浅拷贝。

求证：

Model :

#import 

@interface Model : NSObject 

@property (nonatomic,strong) NSString *name;
@property (nonatomic,assign) NSInteger age;

@end

#import "Model.h"

@implementation Model

- (id)copyWithZone:(NSZone *)zone
{
    Model *copyModel = [[[self class] allocWithZone:zone] init];
    copyModel.name = self.name;
    copyModel.age = self.age;
    return copyModel;
}

@end

调用：

Model *model1 = [[Model alloc] init];
    model1.name = @"model1";
    model1.age = 1;
    
    Model *model2 = [[Model alloc] init];
    model2.name = @"model2";
    model2.age = 2;
    
    Model *model3 = [[Model alloc] init];
    model3.name = @"model3";
    model3.age = 3;
    
    NSArray *array1 = [NSArray arrayWithObjects:model1,model2,model3, nil];
    for (Model *model in array1) {
        NSLog(@"model%ld == %p",(long)[array1 indexOfObject:model],model);
    }
    NSLog(@"array1 == %p",array1);
    

    /*
     - (instancetype)initWithArray:(NSArray *)array
     copyItems:(BOOL)flag
     注意当数组的元素不遵守copy协议的时候flag ＝ NO
     只有当数组的元素遵守copy协议的时候 flag ＝ YES，实现深拷贝
     */
    
    NSArray *copyArray1 = [[NSArray alloc] initWithArray:array1 copyItems:NO];
    for (Model *model in copyArray1) {
        NSLog(@"model%ld == %p",(long)[copyArray1 indexOfObject:model],model);
    }
    
    NSLog(@"copyArray1 == %@",copyArray1);

答应结果：

     原始的数组array1

     2015-09-10 15:17:59.259 CopyTest[30759:2883797] model0 == 0x7f800ac12d90

     2015-09-10 15:17:59.259 CopyTest[30759:2883797] model1 == 0x7f800ac0d870

     2015-09-10 15:17:59.259 CopyTest[30759:2883797] model2 == 0x7f800ac0ade0

     

     

    Model遵守 copy协议下 NSArray *copyArray1 = [[NSArray alloc] initWithArray:array1 copyItems:YES];

     

     2015-09-10 15:17:59.260 CopyTest[30759:2883797] model0 == 0x7f800b00abe0

     2015-09-10 15:17:59.260 CopyTest[30759:2883797] model1 == 0x7f800b008d90

     2015-09-10 15:17:59.260 CopyTest[30759:2883797] model2 == 0x7f800b012650

此文可以参考 

IOS开发之深拷贝与浅拷贝(mutableCopy与Copy)详解  进行理解深拷贝与浅拷贝。