#import

@interfaceViewController :UIViewController

//block 定義 無返回值 傳值obj

typedefvoid(^myblock)(idobj);

-(void)creatandblock:(myblock)block;

@end

@interfaceViewController()

@property(nonatomic,assign)intnumber;

//定義一個返回值為Void，名為blockBack的Block。傳值為字符串。

@property(nonatomic,copy)void(^blockBack)(NSString*valuename);

@end

//定義block

typedefvoid(^myblock)(idobj);

@implementationViewController

//添加Block的類型的進行傳值

-(void)creatandblock:(myblock)block

{

}

- (void)viewDidLoad {

[superviewDidLoad];

[selfcreatNSstring:@"xiao"andBlock:^(idobj) {

obj =@"abc";

}];

}

-（void)creatwithBlock:(myblock)block

{

}

-(void)creatNSstring:(NSString*)name andBlock:(myblock)block

{

block(@"acb");

}

- (void)didReceiveMemoryWarning {

[superdidReceiveMemoryWarning];

}

@end

在iOS 編程中發(fā)現(xiàn)Capturng 'self' strongly in this block is likely to lead to a retain cycle 的警告，告訴其，造成的是Block代碼塊的循環(huán)引用。

使用方法

__weaktypeof(self) weakself =self;

self.popView.selectRowAnIndex= ^(NSIntegerindex)

{

NSString*str =? weakself.array[index];

NSLog(@"%@",str);

};

就是將self用弱引用的weakself替代。

主要造成循環(huán)引用的問題是 當(dāng)前類調(diào)用Block ,block內(nèi)部還有當(dāng)前類，就會造成循環(huán)引用，可以將當(dāng)前的類用__weak typeof(當(dāng)前類) weak+當(dāng)前類 = 當(dāng)前類

void (^dealingResult)(NSArray *)= ^(NSArray *statues){

設(shè)計的一個block調(diào)用直接dealingResult();返回值為void

};