block传值时遇到的问题

#import "ViewController.h"

#import "MyOperation.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

    [superviewDidLoad];

    NSOperationQueue*deque=[[NSOperationQueuealloc]init];

   UIImageView*imageview=[[UIImageViewalloc]initWithFrame:self.view.frame];

    [self.viewaddSubview:imageview];

    

   MyOperation*operation3=[[MyOperationalloc]init];

    operation3.str=@"http://news.xinhuanet.com/world/2015-10/22/128344315_14454681824761n.jpg";

－－－－－－－关于代码块传值，遇到了两次崩掉了原因都是self.myBlock(image)崩掉了，这个问题的解决方法：self.block(参数)所在的方法写在block赋值的后面才行，绝不能写在前面，否则就会崩；block的使用顺序为 ：声明——赋值——引用，引用一定要在赋值的后面，否则就会引发错误。－－－－－－－－－－－－－－－－－

    operation3.myBlock=^void(UIImage*image){

        imageview.image=image;

    };

    [operation3one];

    [dequeaddOperation:operation3];

    // Do any additional setup after loading the view, typically from a nib.

}

- (void)didReceiveMemoryWarning {

    [superdidReceiveMemoryWarning];

    // Dispose of any resources that can be recreated.

}

@end

－－－－－－－－－－//  MyOperation.h－－－－－－－－－－－－－－－－－

#import <Foundation/Foundation.h>

#import <UIKit/UIKit.h>

@interface MyOperation :NSOperation

@property(nonatomic,copy)void(^myBlock)(UIImage*);

@property(nonatomic,copy)NSString*str;

-(void)one;

@end

－－－－－－－－－－－－－//  MyOperation.m－－－－－－－－－－－－－－－

#import "MyOperation.h"

@implementation MyOperation

-(void)one;

{

    NSData*data=[NSDatadataWithContentsOfURL:[NSURLURLWithString:self.str]];

   UIImage*image=[UIImageimageWithData:data];

   self.myBlock(image);

}

@end