IOS開發之Block的使用和記憶體管理

使用Block可簡化回調；

Block 形式： 傳回類型(^ Block名)(形式參數){實體;};

Block Pointer指針：  傳回類型(^Block名)(形式參數);

可用typedof申明；

Block按在記憶體中的位置分為 NSGlobalBlock、NSStackBlock、NSMallocBlock；

ARC中将會自動把NSStackBlock複制到NSMallocBlock；

NSMallocBlock隻需要對NSStackBlock進行copy操作就可以擷取，但是retain操作就不行,

小Demo如下：

<span style="font-size:18px;">#import "ViewController.h"


typedef void(^MyBlock)(void);

@interface ViewController()

@property (nonatomic, strong) MyBlock myblock;

@property (nonatomic, assign)int globalData ;

@end




@implementation ViewController


- (void)viewDidLoad {
    
    int i = 0;
    static int staticI = 0;
    
    __weak ViewController *viewCon = self;
    
    _myblock = ^(void){
        NSLog(@"\ni = %d\n staticI = %d\n globaldata = %d",i,staticI,viewCon.globalData);
        
    };
    
    i++;
    staticI++;
    _globalData++;
    
    
    
    _myblock();
    
    
}

-(void)showMessage{
    NSLog(@"this is private method showMessage");
}



@end</span>           

輸出結果為：

i = 0 staticI = 1 globaldata = 1

參考文獻：

Block入門：http://www.jianshu.com/p/17872da184fb

Block記憶體管理：http://www.knowsky.com/883942.html

http://www.cocoachina.com/bbs/read.php?tid=87593&keyword=block

     http://www.cocoachina.com/bbs/read.php?tid=88591&keyword=block

     http://www.cocoachina.com/bbs/read.php?tid=9222&keyword=block