ios开发基本数据类型和结构体的封装与解封 －－ 妖妖
//知识：
//因为基本数据类型和结构体不是继承自NSObject,所以它们不可以直接存放到数组和字典中。
//数组和字典中只能存储对象类型，其他基本类型和结构体是没有办法放到数组和字典中的，当然你也是无法给它们发送消息的（也就是说有些NSObject的方法是无法调用的），这个时候通常会用到装箱（boxing）和拆箱（unboxing）。但是在ObjC中装箱的过程必须手动实现，ObjC不支持自动装箱。
//在ObjC中我们一般将基本数据类型装箱成NSNumber类型（当然它也是NSObject的子类，但是NSNumber不能对结构体装箱），调用其对应的方法进行转换：
@interface c (NSNumberCreation)
//基本数据类型的封装
+ (NSNumber *)numberWithChar:(char)value;
+ (NSNumber *)numberWithUnsignedChar:(unsigned char)value;
+ (NSNumber *)numberWithShort:(short)value;
+ (NSNumber *)numberWithUnsignedShort:(unsigned short)value;
+ (NSNumber *)numberWithInt:(int)value;
+ (NSNumber *)numberWithUnsignedInt:(unsigned int)value;
+ (NSNumber *)numberWithLong:(long)value;
+ (NSNumber *)numberWithUnsignedLong:(unsigned long)value;
+ (NSNumber *)numberWithLongLong:(long long)value;
+ (NSNumber *)numberWithUnsignedLongLong:(unsigned long long)value;
+ (NSNumber *)numberWithFloat:(float)value;
+ (NSNumber *)numberWithDouble:(double)value;
+ (NSNumber *)numberWithBool:(BOOL)value;
+ (NSNumber *)numberWithInteger:(NSInteger)value NS_AVAILABLE(10_5, 2_0);
+ (NSNumber *)numberWithUnsignedInteger:(NSUInteger)value NS_AVAILABLE(10_5, 2_0);
//基本数据类型的解封
@property (readonly) char charValue;
@property (readonly) unsigned char unsignedCharValue;
@property (readonly) short shortValue;
@property (readonly) unsigned short unsignedShortValue;
@property (readonly) int intValue;
@property (readonly) unsigned int unsignedIntValue;
@property (readonly) long longValue;
@property (readonly) unsigned long unsignedLongValue;
@property (readonly) long long longLongValue;
@property (readonly) unsigned long long unsignedLongLongValue;
@property (readonly) float floatValue;
@property (readonly) double doubleValue;
@property (readonly) BOOL boolValue;
@property (readonly) NSInteger integerValue NS_AVAILABLE(10_5, 2_0);
@property (readonly) NSUInteger unsignedIntegerValue NS_AVAILABLE(10_5, 2_0);
@property (readonly, copy) NSString *stringValue;
例子：
//封装
NSNumber *number=[NSNumber numberWithInt:2];
NSArray *array=[NSArray arrayWithObject:number];
//解封
[number intValue];
//结构体呢的封装和解封需要引入另外一个类型NSValue，其实上面的NSNumber就是NSValue的子类，它包装了一些基本数据类型的常用装箱、拆箱方法，而NSValue可以对任何数据类型进行装箱、拆箱操作。
//对于常用的结构体Foundation已经为我们提供好了具体的装箱方法如下：
@interface NSValue (NSValueUIGeometryExtensions)
//结构体的封装
+ (NSValue *)valueWithCGPoint:(CGPoint)point;
+ (NSValue *)valueWithCGVector:(CGVector)vector;
+ (NSValue *)valueWithCGSize:(CGSize)size;
+ (NSValue *)valueWithCGRect:(CGRect)rect;
+ (NSValue *)valueWithCGAffineTransform:(CGAffineTransform)transform;
+ (NSValue *)valueWithUIEdgeInsets:(UIEdgeInsets)insets;
+ (NSValue *)valueWithUIOffset:(UIOffset)insets NS_AVAILABLE_IOS(5_0);
//结构体的解封
- (CGPoint)CGPointValue;
- (CGVector)CGVectorValue;
- (CGSize)CGSizeValue;
- (CGRect)CGRectValue;
- (CGAffineTransform)CGAffineTransformValue;
- (UIEdgeInsets)UIEdgeInsetsValue;
- (UIOffset)UIOffsetValue NS_AVAILABLE_IOS(5_0);
//封装
CGPoint point=CGPointMake(10, 20);
NSValue *value=[NSValue valueWithCGPoint:point];//对于系统自带类型一般都有直接的方法进行包装
NSArray *array=[NSArray arrayWithObject:value];//放倒数组中
//解封
CGPoint point1=[value CGPointValue];
//自定义结构体的封装与解封
typedef struct{ //自定义一个结构体Student
int age;
int number;
}Student;
Student stu;
stu.age = 10;
stu.number = 100;
NSValue *va = [NSValue value:&stu withObjCType:@encode(Student)];
Student value2;//定义一个结构体变量来接受从NSValue得到的结构体
[va getValue:&value2];//把va对象中的结构体取出来
int a=value2.age; //取得结构体中的字段