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详解IOS 单例的两种方式

时间:2021-03-30 16:19     来源/作者:iOS开发网

详解IOS 单例的两种方式

方法一:

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#pragma mark -
#pragma mark sharedSingleton methods
 
//单例函数
static RtDataModel *sharedSingletonManager = nil;
 
+ (RtDataModel *)sharedManager
{
  @synchronized(self) {
    if (sharedSingletonManager == nil) {
      sharedSingletonManager = [[self alloc] init];
    }
  }
  return sharedSingletonManager;
}
 
+ (id)allocWithZone:(NSZone *)zone
{
  @synchronized(self) {
    if (sharedSingletonManager == nil) {
      sharedSingletonManager = [super allocWithZone:zone];
      return sharedSingletonManager; // assignment and return on first allocation
    }
  }
  return nil; //on subsequent allocation attempts return nil
}
 
- (id)copyWithZone:(NSZone *)zone
{
  return sharedSingletonManager;
}
 
- (id)retain
{
  return sharedSingletonManager;
}
 
- (NSUInteger)retainCount
{
  return UINT_MAX; //denotes an object that cannot be released
}
 
- (oneway void)release
{
  //do nothing
}
 
- (id)autorelease
{
  return sharedSingletonManager;
}
 
//单例函数结束

方法二:

.h文件

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#import <Foundation/Foundation.h>
 
@interface RtTestDataModel : NSObject
{
  NSMutableArray      * _buyDataTArray;
  NSMutableArray      * _sellDataTArray;
}
 
+ (RtTestDataModel *)sharedManager;
 
- (void)addOptionBuyDataArrayModel: (NSMutableArray *)DataArray;
- (NSMutableArray *)getOptionBuyDataArrayModel;
 
@end

.m文件

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#import "RtTestDataModel.h"
 
@implementation RtTestDataModel
 
+ (RtTestDataModel *)sharedManager
{
  static RtTestDataModel *sharedManager = nil;
  static dispatch_once_t predicate;
   
  dispatch_once(&predicate,^{
    sharedManager = [[RtTestDataModel alloc]init];
  });
 
  return sharedManager;
}
 
- (void)dealloc
{
  [_buyDataTArray removeAllObjects];
  [_buyDataTArray release];
   
  [super dealloc];
}
 
- (id)init
{
  self = [super init];
   
  if (self != nil) {
    _buyDataTArray = [[NSMutableArray alloc] initWithCapacity:8];
  }
  return self;
}
 
- (void)addOptionBuyDataArrayModel: (NSMutableArray *)DataArray{
   
  if (DataArray != nil) {
     
    [_buyDataTArray removeAllObjects];
    [_buyDataTArray addObjectsFromArray:DataArray];
  }
}
 
- (NSMutableArray *)getOptionBuyDataArrayModel{
   
  return _buyDataTArray;
}
@end

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原文链接:http://blog.csdn.net/robinson_911/article/details/44786429

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