iOS -copy&mutableCopy

標籤：

1、對於非容器物件（NSString）

不可變 （NSString）

copy ：淺複製，指標指向

mutableCopy：深複製，產生可變字串對象

可變（NSMutableString）

copy： 深複製，產生不可變字串對象

mutableCopy ：深複製，產生可變字串對象

2、對於容器類對象 數組

不可變（NSArray）

copy ：淺複製，指標指向

mutableCopy：深複製，產生可變數組對象（但，數組中的對象沒有進行處理的話，數組的中的對象是淺複製）

可變（NSMutableArray）

copy ：深複製，產生不可變數組對象

mutableCopy：深複製，產生不可變數組對象

test:

    NSString *str1 = @"123";    NSLog(@"%p",str1);    NSString *str2 = [str1 copy];    NSLog(@"%p",str2);    NSMutableString *str3 = [str1 mutableCopy];    NSLog(@"%p",str3);        NSMutableString *str4 = [[NSMutableString alloc]initWithString:@"123"];    NSLog(@"%p",str4);    NSString *str5 = [str4 copy];    NSLog(@"%p",str5);    NSMutableString *str6 = [str4 mutableCopy];    NSLog(@"%p",str6);        NSArray *array1 = [[NSArray alloc] initWithObjects:@3,@4, nil];    NSLog(@"%p",array1);    NSArray *array2 = [array1 copy];    NSLog(@"%p",array2);    NSMutableArray *array3 = [array1 mutableCopy];    NSLog(@"%p",array3);        NSMutableArray *array4 = [[NSMutableArray alloc]initWithObjects:@2,@3, nil];    NSLog(@"%p",array4);    NSArray *array5 = [array4 copy];    NSLog(@"%p",array5);    NSMutableArray *array6 = [array4 mutableCopy];    NSLog(@"%p",array6);

2016-08-23 10:54:50.878 [1364:147504] 0x10409cc902016-08-23 10:54:53.636 [1364:147504] 0x10409cc902016-08-23 10:54:53.636 [1364:147504] 0x7fd602d1c3302016-08-23 10:54:54.322 [1364:147504] 0x7fd602dae1902016-08-23 10:54:54.323 [1364:147504] 0xa0000000033323132016-08-23 10:54:54.323 [1364:147504] 0x7fd602e074202016-08-23 10:54:55.924 [1364:147504] 0x7fd602d00d602016-08-23 10:54:56.750 [1364:147504] 0x7fd602d00d602016-08-23 10:54:56.750 [1364:147504] 0x7fd602c110502016-08-23 10:54:56.751 [1364:147504] 0x7fd602c2bfc02016-08-23 10:54:56.751 [1364:147504] 0x7fd602c0a0702016-08-23 10:54:56.751 [1364:147504] 0x7fd602c0a220

 

3、NSHashTable -NSMapTable

NSHashTable 和 -NSMapTable是iOS 6 後出現的容器類對象，他有一個特點就是，對加入其中的對象，可以設定其為弱引用,

而不是像數組等容器加入對象後預設對象引用計數會加1，強引用，有點類似（weak,assgin）的容器

- (instancetype)initWithOptions:(NSPointerFunctionsOptions)options capacity:(NSUInteger)initialCapacity NS_DESIGNATED_INITIALIZER;typedef NS_OPTIONS(NSUInteger, NSPointerFunctionsOptions) {    // Memory options are mutually exclusive        // default is strong    NSPointerFunctionsStrongMemory NS_ENUM_AVAILABLE(10_5, 6_0) = (0UL << 0),       // use strong write-barrier to backing store; use GC memory on copyIn#if (TARGET_OS_MAC && !(TARGET_OS_EMBEDDED || TARGET_OS_IPHONE)) || TARGET_OS_WIN32    NSPointerFunctionsZeroingWeakMemory NS_ENUM_DEPRECATED_MAC(10_5, 10_8) = (1UL << 0),  // deprecated; uses GC weak read and write barriers, and dangling pointer behavior otherwise #endif    NSPointerFunctionsOpaqueMemory NS_ENUM_AVAILABLE(10_5, 6_0) = (2UL << 0),    NSPointerFunctionsMallocMemory NS_ENUM_AVAILABLE(10_5, 6_0) = (3UL << 0),       // free() will be called on removal, calloc on copyIn    NSPointerFunctionsMachVirtualMemory NS_ENUM_AVAILABLE(10_5, 6_0) = (4UL << 0),    NSPointerFunctionsWeakMemory NS_ENUM_AVAILABLE(10_8, 6_0) = (5UL << 0),         // uses weak read and write barriers appropriate for ARC or GC        // Personalities are mutually exclusive    // default is object.  As a special case, ‘strong‘ memory used for Objects will do retain/release under non-GC    NSPointerFunctionsObjectPersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (0UL << 8),         // use -hash and -isEqual, object description    NSPointerFunctionsOpaquePersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (1UL << 8),         // use shifted pointer hash and direct equality    NSPointerFunctionsObjectPointerPersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (2UL << 8),  // use shifted pointer hash and direct equality, object description    NSPointerFunctionsCStringPersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (3UL << 8),        // use a string hash and strcmp, description assumes UTF-8 contents; recommended for UTF-8 (or ASCII, which is a subset) only cstrings    NSPointerFunctionsStructPersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (4UL << 8),         // use a memory hash and memcmp (using size function you must set)    NSPointerFunctionsIntegerPersonality NS_ENUM_AVAILABLE(10_5, 6_0) = (5UL << 8),        // use unshifted value as hash & equality    NSPointerFunctionsCopyIn NS_ENUM_AVAILABLE(10_5, 6_0) = (1UL << 16),      // the memory acquire function will be asked to allocate and copy items on input};

 

4、iOS 中的Keychain API

ios 中的keychian 應該是一個系統級的單例，在裡面存的資訊，安全的程度比較高，

不同的app可以通過相同的key,度取相關的資訊，簡單實現不同app之間的資訊共用一種思路

iOS -copy&mutableCopy