关于寒假学习objective-c的感想

买了本《learn objective-c on Mac》，一开始买来看起来还蛮薄的，250页，看了后，发现语言都有很多共同的地方，新的特性都从C++和java类似过来，就是换了个名字，感觉看了以后感觉收获蛮大，虽然只接触了点皮毛。

1.C语言知识

2.了解了xcode使用

3.懂得了一些新语法和新特性。

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1.正式协议 与 非正式协议(被@optional的正式协议代替) 与文件加载保存

@required 一定要实现

@optional 选择性实现

例1.

@protocol NSCopying //深度复制复制

-(id) copyWithZone:(NSZone*)zone;

@end

NSArray的copy为浅复制

@protocol NSCoding //编码与解码

-(void)encodeWithCoder:(NSCoder*)acoder;

-(id)initWithCoder:(NSCoder*)decoder;

NSCoding可用于将任何对象编码为NSData NSData可用 [data writeToFile:"tmp.txt" atomically:true] 存入硬盘

例1：

@interface A:NSObject<NSCopying,NSCoding>

{

       NSString*name;

}

@property(copy) NSString*name;

@end

@implementation A

@synthesize name;

-(id)copyWithZone:(NSZone*)zone
{

      A *a;
      a=[[[self class]allocWithZone:zone]init];
      a.name=self.name;
      return a;
}

-(void)encodeWithCoder:(NSCoder*)acoder
{
    [acoder codeWithObject:name forKey:@"name"];
}
-(id)initWithCoder:(NSCoder*)decoder
{
    if(self=[super init])
    {
        NSString*n=[decoder decodeObjectForKey:@"name"];
 
    }
    return self;
}

通过NSKeyedArchiver类进行编码为NSData

NSData*data=[NSKeyedArchiver archivedDataWithRootObject:对象];自动调用encodeWithCoder

A *a=[NSKeyedUnarchiver unarchiveObjectWithData:data]; //解码

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属性列表 NSArray NSDictionary NSString NSNumber NSDate NSData

1.NSArray

+(id)arrayWithObject:... 以nil结尾

-(unsigned)count;

-(id)objectAtIndex:(unsigned) index;

NSMutableArray

+(id)arrayWithCapacity:(int);

-(void)addObject:(NSObject);

-(void)removeObjectAtIndex:(int)index;

2.NSDictionary

+(id)dicitonaryWithObjectsAndKeys:(id)firstObject,(NSString*)firstkey...;

-(id)objectForKey:(id)key;

NSMutableDictionary

+(id)dicitonaryWithCapacity:(int)n;

-(void)setObject:(id) object forKey:(id)key;

-(void)removeObjectForKey:(id)key;

3.NSNumber

封装标准类型

NSNumber*a=[NSNumber numberWithInt:10];

4.NSDate

+(NSDate*)date;

+(NSDate*)dateWithTimeIntervalSinceNow:(int)a;

5.NSData

+(NSData*)dataWithBytes:(NSObject) length:(int);

-(int)length;

-(NSObject) bytes;

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谓词:

谓词实际上就是用简单的方式给出限制条件 可以用for 和if来替代

NSPredicate:

+(NSPredicate)predicateWithFormat:....

-(NSArray*)filteredArrayUsingPredicate:predicate;

例：

@interface A :NSObject
{
	NSString*name;
}
@property NSString*name;
@end
@implementation A
@synthesize name;
@end
@interface B;NSObject
{
	NSMutableArray*a;
}
@end
@implementation B
-(void)addA(NSString*n)
{
	A*object;
	object.name=n;
	a.add(object);
}
@end
int main()
{
	B* bObject=[[B alloc]init];
	bObject.addA("A");
	bObject.addA("B");
	bObject.addA("C");
	bObject.addA("D");
	NSPredicate*predicate=[NSPredicate predicateWithFormat:@"name=%@","A"];
	NSArray*result=[bObject filteredArrayUsingPredicate: predicate];    

}

谓词还给了很多的运算符（可以沿用C的运算符）

例：沿用上了例子的类

NSPredicate*predicate=[NSPredicate predicateWithFormat:@"(name=='A')AND(name=='B')"];

数组运算符 name BETWEEN{MIN,MAX};

name IN{"A","B"};

SELF的运用：

NSArray*a=[NSArray arrayWithObject:@"A","B",nil];

NSPredicate*predicate=[NSPredicate predicateWithFormat:@SELF IN "'A','B' "];

NSArray* b=[a filteredArrayUsingPredicate:predicate];

字符串运算符：

BEGINSWITH

ENDSWITH

CONTAINS

[c]忽略大小写

[d]忽略重音符

[cd]都忽略

例： BEGINSWITH[c]

LIKE运算符

LIKE '*A*' 中间包含A即可

LIKE '??A*'前面有两个字符