NSNumber

NSNumber*intNum = [[NSNumberalloc]initWithInt:5];

NSNumber*floatNum = [[NSNumberalloc]initWithFloat:5.0f];

NSNumber*doubleNum = [[NSNumberalloc]initWithDouble:5.0f];

NSNumber*charNum = [[NSNumberalloc]initWithChar:'A'];

//或者...

//        NSNumber *intNum1 = [NSNumber numberWithInt:6];

//        NSNumber *floatNum1 = [NSNumber numberWithFloat:6.0];

//        NSNumber *doubleNum1 = [NSNumber numberWithDouble:6.0];

//        NSNumber *charNum1 = [NSNumber numberWithChar:'A'];

if([intNumcompare:floatNum] ==NSOrderedAscending) {

NSLog(@" < ");

}elseif([intNumcompare:floatNum] ==NSOrderedDescending){

NSLog(@" > ");

}elseif([intNumcompare:floatNum] ==NSOrderedSame){

NSLog(@" == ");

}

BOOLb = [intNumisEqualToNumber:floatNum];

NSLog(@"======%d",b);

NSLog(@"---- %d -----",[intNumintValue]);

NSLog(@"---- %f -----",[floatNumfloatValue]);

NSLog(@"---- %f -----",[doubleNumdoubleValue]);

NSLog(@"---- %c -----",[charNumcharValue]);

输出：

2015-09-24 10:06:04.394 test[1475:395290]  <

2015-09-24 10:06:04.396 test[1475:395290] ======1

2015-09-24 10:06:04.396 test[1475:395290] ---- 5 -----

2015-09-24 10:06:04.396 test[1475:395290] ---- 5.000000 -----

2015-09-24 10:06:04.396 test[1475:395290] ---- 5.000000 -----

2015-09-24 10:06:04.396 test[1475:395290] ---- A——

1.strong :除NSString\block以外的OC对象

@property(nonatomic,strong) NSArray  *<#model#>;

2.weak：各种UI控件(但不是绝对，也有控件要使用strong属性的)

@property (nonatomic,weak) UIButton *button;

3.assign：CGFloat，NSInteger等基本数据类型、枚举、结构体（非OC对象）

@property(nonatomic,assign) CGFloat <#model#>;

4.copy：

copy : 创建的是不可变副本(如NSString、NSArray、NSDictionary)

mutableCopy :创建的是可变副本(如NSMutableString、NSMutableArray、NSMutableDictionary)

@property(nonatomic,copy)NSString *<#model#>;

•@property内存管理策略的选择

•1.非ARC

• 1> copy : 只用于NSString\block

• 2> retain : 除NSString\block以外的OC对象

• 3> assign : 基本数据类型、枚举、结构体（非OC对象），当2个对象相互引用，一端用retain，一端用assign

•2.ARC

• 1> copy : 只用于NSString\block

• 2> strong : 除NSString\block以外的OC对象

• 3> weak : 当2个对象相互引用，一端用strong，一端用weak

• 4> assgin : 基本数据类型、枚举、结构体（非OC对象）