Customization of iOS Development a single case

Customization of iOS Development a single case

Here I use macros:

. h
#define SINGLE_INTERFACE (Class) + (class *) shared# #class;

. m
\ represents the next line also belongs to the macro
# # is a delimiter

• #define SINGLE_IMPLEMENTATION (Class) \
• Static class *_instance; \
• \
• + (class *) shared# #class \
• { \
• if (_instance = = nil) {\
• _instance = [[Self alloc] init]; \
• } \
• return _instance; \
• } \
• \
• + (ID) Allocwithzone: (nszone *) zone \
• { \
• static dispatch_once_t Oncetoken; \
• Dispatch_once (&oncetoken, ^{\
• _instance = [Super Allocwithzone:zone]; \
• }); \
• return _instance; \
• }

Of course there are other more comprehensive methods, but the above drink on the principle is the same, usually used in the above can be useful.
The singleton pattern is different in the ARC\MRC environment, it needs to write 2 different sets of code
#if __has_feature (OBJC_ARC)
//arc

Override Allocwithzone: Method, create a unique instance here (Note thread safety)

• + (ID) allocwithzone: (struct _nszone *) zone
• {
• @synchronized (self) {
• if (!_instance) {
• _instance = [Super Allocwithzone:zone];
• }
• }
• return _instance;
• }
• Provides 1 class methods for external access to unique instances
• + (Instancetype) shareinstance
• {
• @synchronized (self) {
• if (!_instance) {
• _instance = [[Self alloc] init];
• }
• }
• return _instance;
• }
• Implementing Copywithzone: Methods
• + (ID) copywithzone: (struct _nszone *) zone
• {
• return _instance;
• }

#else
//Non-arc

Non-arc (MRC), single-instance mode implementation (several steps more than ARC)


Override Allocwithzone: Method, create a unique instance here (Note thread safety)

• + (ID) allocwithzone: (struct _nszone *) zone
• {@synchronized (self) {
• if (!_instance) {
• _instance = [Super Allocwithzone:zone];
• }
• }
• return _instance;
• }
• Provides 1 class methods for external access to unique instances
• + (Instancetype) shareinstance
• {
• @synchronized (self) {
• if (!_instance) {
• _instance = [[Self alloc] init];
• }
• }
• return _instance;
• }
• Implementing Copywithzone: Methods
• + (ID) copywithzone: (struct _nszone *) zone
• {
• return _instance;
• }
• Implementing a memory management approach
• -(ID)retain
• {
• return self;
• }
• -(Nsuinteger)Retaincount
• {
• return 1;
• }
• -(OneWay void)release
• {
• }
• -(ID)autorelease
• {
• return self;
• }

#endif

Customization of iOS Development a single case