Block---例子

 

#import <Foundation/Foundation.h>

 

@interface DemoObj : NSObject

 

- (void)demoBlockOp;

 

@end

 

#import "DemoObj.h"

 

@interface DemoObj()

 

@property (nonatomic, strong) NSOperationQueue *queue;

 

@end

 

@implementation DemoObj

 

- (instancetype)init

{

    self = [super init];

    if (self) {

        self.queue = [[NSOperationQueue alloc] init];

    }

    

    return self;

}

 

- (void)dealloc

{

    NSLog(@"demoobj dealloc");

}

 

- (void)demoOp:(id)obj

{

    NSLog(@"%@ %@", [NSThread currentThread], obj);

}

 

- (void)demoBlockOp

{

    // 不能用__weak

//    __weak DemoObj *weakSelf = self;

    // 只有self直接强引用block，才会出现循环引用

    // block的管理以及线程的创建和销毁是由队列负责的，直接在block中使用self没有关系！

    for (int i = 0; i < 10; ++i) {

        

        [self.queue addOperationWithBlock:^{

            [self demoOp:@(i)];

        }];

    }

}

 

@end

 

#import <UIKit/UIKit.h>

 

@interface MJViewController : UIViewController

 

@end

#import "MJViewController.h"

#import "DemoObj.h"

 

@interface ViewController ()

 

@end

 

@implementation ViewController

 

- (void)viewDidLoad

{

    [super viewDidLoad];

 

    DemoObj *obj = [[DemoObj alloc] init];

    

    [obj demoBlockOp];

}

 

@end