block 理解及 简单回调

block 就是一个代码块,上代码：

TestBlock类中  就是定义block     给 block 传入参数  ,“方法”体里   留到回调的地方   实现

#import <Foundation/Foundation.h>

typedef void (^BlockCallBack)(NSString *SayWhat);

@interface TestBlock : NSObject
{
    BlockCallBack bcb;


}
@property(nonatomic,assign)BlockCallBack bcb;
-(void)initBcb:(id)entity:(BlockCallBack)bcb1;
@end

#import "TestBlock.h"
#import <objc/runtime.h>
@implementation TestBlock
@synthesize bcb;

-(void)initBcb:(id)entity :(BlockCallBack)bcb1
{
    const char *name=   object_getClassName(entity);
  
    self.bcb=bcb1;
    if (bcb) {
        bcb([[NSString alloc] initWithUTF8String:name]);
    }else
    {
        NSLog(@"参数  bcb1 未实现...");
    
    }
    

}





-(void)dealloc
{
    
    [super dealloc];

}
@end

再joce 类中  （一人名  简单事例   不太规范）

回调 block   得到参数   实现 “方法”体

#import <Foundation/Foundation.h>
#import "TestBlock.h"
@interface Joce : NSObject
{
    TestBlock *tb;


}
@property(nonatomic,retain)TestBlock *tb;


-(void)sayHello;
@end

#import "Joce.h"

@implementation Joce
@synthesize tb;


-(void)sayHello
{

    if (tb) {
        [tb initBcb:self :^(NSString *name){
        
        
            NSLog(@"%@ Say Hello Word!!!!!!",name);
        
        
        
        }];
    }else
    {
    
        NSLog(@"请实例化 joce");
    
    }



}

-(void)dealloc
{

    [tb release];
    [super dealloc];
}


@end

ok....

希望下次能再  项目中用到....