LHF Objective-C语法（2）类

最新推荐文章于 2012-02-22 17:56:18 发布

转载最新推荐文章于 2012-02-22 17:56:18 发布 · 482 阅读

文章标签：

#float #interface #getter #class #setter #优化

本文深入探讨了Objective-C与Swift两种编程语言在iOS开发领域的应用，包括它们各自的优势、特点以及如何在实际项目中进行选择与使用。

Fraction.h （分数）

#import <Foundation/Foundation.h>

static int t= 0;
@interface Fraction : NSObject{
	int numerator; //分子
	@public int denominator; //分母
}

-(void) setNumerator:(int) numerator;
-(void) setDenominator:(int) denominator;
-(void) setNumerator:(int) numerator andDenominator:(int) denominator;

-(int) numerator;
-(int) denominator;
-(void) print;
+(void) t;

@end

解释:

1、#import <Foundation/Foundation.h>导入系统头文件 #import "Other.h" 导入普通头文件

2、类变量定义在接口外，类变量只能本类访问

3、花括号里是实例变量访问修饰符可以是 @public @protected @private

4、默认是@protected 除了实例变量有访问修饰符，其他（类变量，类方法，成员方法）都没有

5、所以方法都是公有的，所以类变量都是私有的

6、- 为成员方法 + 为类方法

7、大多类方法都是被用来初始化对象的

Fraction.m

//================================================
#import "Fraction.h"

@implementation Fraction
-(void) setNumerator:(int) n{
	numerator = n;
}

-(void) setDenominator:(int) d{
	denominator = d;
}

-(void) setNumerator:(int) n andDenominator:(int) d{
	numerator = n;
	denominator = d;
}

-(int) numerator{
	return numerator;
}

-(int) denominator{
	return denominator;
}

-(void) print{
	NSLog(@"%d/%d",numeraotr,denominator);
}

-(void) m{
	NSLog(@"-m:The class varable t is %d",++t);
}

+(void) t{
	NSLog(@"+t:The class varable t is %d",++t);
}

@end

1、m方法没有在头文件中声明，也可以调用

2、方法的本地变量（参数，方法中定义的变量）改成缩写了，防止重名。在名称冲突情况下，会隐藏实例变量

int main(int argc,const char * argv[]){
	Fraction *frac = [[Fraction alloc] init];
	[frac setNumerator:3 andDenominator:5];
	[frac print];
	NSLog(@"The denominator of Fration is %d\n",frac->denominator);
	[Fraction t];
	[frac m];
	[frac release];
	return 0;
}

1、第5行调用了成员变量denominator（因为是public的） numerator是protected 只能本类，子类访问

2、第6行调用了类方法，也可以用下边方法调用类方法

[[Fraction class] t];

Class clazz = [Fraction class]; [clazz t]; clzaa是指针，没有*

3、第7行 m方法，未在头文件中声明，这里也可以调用，相当私有化了

4、第7行释放了frac 申请的内存空间

5、属性访问器（@property）

//Person.h头文件================================

#import <Foundation/Foundation.h>

@interface Person :NSObject{//创建类

NSString *name;//属性

int age;//属性

}

-(void) setName:(NSString*) n;//要吧这3个方法用属性访问器替换掉

-(void) setAge:(int) a;

-(NSString*) name;

-(void) print;

@end

//Person.m实现文件================================

@implementation Person

-(void) setName:(NSString*) n{

[ n retain];

[name release];

[name = n];

}

-(void) setAge:(int) a{

age = a;

}

-(NSString*) name{

return name;

}

-(void) print{

NSLog(@"This is a method...");

}

@end

//main.m================================

int main(int argc,const char * argv[]){

Person person ;

person = [[Person alloc] init];

[person setName:@"Tom"];

[person setAge:22];

[person print];

[person release];

}

用属性访问器，简化上边代码

参考地址：http://skyoceanone.blog.51cto.com/3483859/687268

//Person.h头文件================================

#import <Foundation/Foundation.h>

@interface Person :NSObject{//创建类

NSString *name;

int age;//属性

}

@property (retain) NSString* name;//set get方法简化

@property (assign) int age;//set方法简化

-(void) print;

@end

//Person.m实现文件================================

@implementation Person

@synthesize name;

@synthesize age;

-(void) print{

NSLog(@"This is a method...");

}

@end

//main.m================================

int main(int argc,const char * argv[]){

Person person ;

person = [[Person alloc] init];

person.name=@"Tom";

person.age = 22;

[person print];

[person release];

}

@property(属性访问器类型) 实例变量类型实例变量

@property(nonatomic,assign) int numerator;

@property float count; //

@property(nonatomic,assign,getter=isMale) BOOL male;

属性访问器类型

assign / retain / copy 普通赋值/带计数器的赋值/拷贝

readonly /readwrite 只读（不生成getter方法）/ 读写

nonatomic 线程不安全（默认线程安全）

getter/setter 给生成的方法起名

另一个例子：

//旧文件
#import <Foundation/Foundation.h>
#import "Tire.h"
@interface AllWeatherRadial :Tire{
	float rainHanding;	//轮胎气压
	float snowHanding;	//花纹深度
}
-(void) setRainHandling:(float) rainHanding;
-(float) rainHanding;
-(void) setSnowHandling:(float) snowHandling;
-(float) snowHandling;
@end	//AllWeatherRadial
//新文件，简化了代码=======================================
#import <Foundation/Foundation.h>
#import "Tire.h"
@interface AllWeatherRadial :Tire{
	float rainHanding;	
	float snowHanding;	
}
@property float rainHandling;//优化后的setter getter 方法
@property float snowHandling;
@end

#import "AllWeatherRadial.h"
@implementation AllWeatherRadial

-(id) initWithPressure:(float) p treadDepth:(float) td{
	if(self =[super initWithPressure: p
			      treadDepth: td]){
		rainHandling = 23.7;
		snowHandling = 42.5;
	}
	return (self);
}
-(void) setRainHandling:(float) rh{
	rainHandling = rh;
}
-(float)rainHandling{
	return rainHandling;
}
-(void) setSnowHandling:(float)sh{
	snowHandling = sh;
}
-(float) snowHandling{
	return snowHandling
}
-(NSString*) description{
	NSString* desc;
	desc = [[NSString alloc] initWithFormat:
			     @"AllWeatherRadial:%.1f/%.1f/%.1f/%.1f",
		[self pressure],[self treadDepth],
		[self rainHandling],
		[self snowHandling]];
	return desc;
}
@end

//新文件简化了代码
#import "AllWeatherRadial.h"
@implementation AllWeatherRadial

@synthesize rainHandling;
@synthesize snowHandling;

-(id) initWithPressure:(float) p treadDepth:(float) td{
	if(self =[super initWithPressure: p
			      treadDepth: td]){
		rainHandling = 23.7;
		snowHandling = 42.5;
	}
	return (self);
}
-(NSString*) description{
	NSString* desc;
	desc = [[NSString alloc] initWithFormat:
			     @"AllWeatherRadial:%.1f/%.1f/%.1f/%.1f",
		[self pressure],[self treadDepth],
		[self rainHandling],
		[self snowHandling]];
	return desc;
}
@end

//main====================================================
int main(int argc,const char * argv[]){
	Car *car  = [[Car alloc] init];
	int i;
	for(i=0;i<4;i++){
		AllWeatherRadial *tire;
		tire = [[AllWeatherRadial alloc] init];
		[tire setRainHandling:20+i];
		[tire setSnowHandling:28+i];
		NSLog(@"the tire's handling is %.f %.f",
				[tire rainHandling],
				[tire snowHandling]);
		[car setTire:tire atIndex:i];
		[tire release];
	}
	Engine *engine = [[Slant6 alloc] init];
	[car setEngine:engine];
	[car print];
	[car release];
	return 0;
}//main