NSObject *object = [[NSObject alloc] init];
[[object autorelease] autorelease];

- (void)method:(NSString *)value,...
{
    //指向变参的指针
    va_list list;
    //使用第一个参数来初使化list指针
    va_start(list, value);
    while (YES)
    {
        //返回可变参数，va_arg第二个参数为可变参数类型，如果有多个可变参数，依次调用可获取各个参数
        NSString *string = va_arg(list, NSString*);
        if (!string) {
            break;
        }
        NSLog(@"%@",string); 
    }
    //结束可变参数的获取
    va_end(list);
}

（1）[self.view endEditing:YES];
（2）[[UIApplication sharedApplication] sendAction:@selector(resignFirstResponder) to:nil from:nil forEvent:nil];
（3）[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

1.@property(nonatomic,retain)NSString *str;
2.@property(nonatomic,copy)NSString *str;

#define  false   0
#define   true    1
#define YES ((BOOL)1)
#define NO  ((BOOL)0)
//例：
BOOL myBool;  (unsigined char)8位中最低位为1就是YES，最低位为0就是NO
myBool = YES;      //True
myBool = TRUE    //True
myBool = 1          //True
myBool = NO      //False
myBool = FALSE  //False
myBool = 0         //False

1、拍击UITapGestureRecognizer (任意次数的拍击)  
2、向里或向外捏UIPinchGestureRecognizer (用于缩放)  
3、摇动或者拖拽UIPanGestureRecognizer  
4、擦碰UISwipeGestureRecognizer (以任意方向)  
5、旋转UIRotationGestureRecognizer (手指朝相反方向移动)  
6、长按UILongPressGestureRecognizer

ClassName *myName = [[[ClassName alloc] init] autorelease];//标记为autorelease
[classA setName:myName]; //retain count == 2
[myName release]; //retain count==1，注意，在ClassA的dealloc中不能release name，否则release pool时会release这个retain count为0的对象，这是不对的。

TODO:Decoder代码

NSString *umdFolder = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/umd"];
NSString *imagePath = [umdFolder stringByAppendingPathComponent:[umd.title md5]];//[umd.title md5]
[[NSFileManager defaultManager] createFileAtPath:imagePath contents:coverImageData attributes:nil];

NSString *umdFolder = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/umd"];
if ([[NSFileManager defaultManager] fileExistsAtPath:umdFolder] == NO)
{
        [[NSFileManager defaultManager] createDirectoryAtPath:umdFolder withIntermediateDirectories:YES attributes:nil error:nil];
}
NSString *imagePath = [umdFolder stringByAppendingPathComponent:[umd.title md5]];//[umd.title md5]
[[NSFileManager defaultManager] createFileAtPath:imagePath contents:coverImageData attributes:nil];

@protocol MyProtocol <NSObject>
//定义一些方法
@end
id <MyProtocol> foo;
//foo符合<MyProtocol,NSObject>

@protocol MyProtocol
//定义一些方法
@end
id <MyProtocol,NSObject> foo;
//或者
NSObject <MyProtocol> * foo;//要保证foo赋值为NSObject的子类对象。

@interface DynamicTest : NSObject
{
        NSString *_str;
}
@property (nonatomic,strong) NSString *str;
@end
@implementation DynamicTest
@dynamic str;
- (void)setStr:(NSString *)tempStr
{
    if (tempStr != _str)
    {
        _str = tempStr;
    }
}
- (NSString *)str
{
    return  _str;
}
@end

@interface Movie : NSManagedObject
{
}
@property (retain) NSString* title;
@end
@implementation Movie
@dynamic title;
@end

//注：id是对象结构体指针,Class是类结构指针
struct objc_class {
    Class isa;
    Class super_class
    const char *name                                         
    long version                                             
    long info                                                
    long instance_size
    struct objc_ivar_list *ivars                             
    struct objc_method_list **methodLists                    
    struct objc_cache *cache                                 
    struct objc_protocol_list *protocols                     
};
typedef struct objc_class *Class;
struct objc_object {
    Class isa;
};
typedef struct objc_object *id;

id result;
[invocation getReturnValue:&result];

void *pointer;
[invocation getReturnValue:&pointer];
id result = (__bridge id)pointer;