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  • Block 使用总结

    - (void)testBlockWeakObj1

    {

        UILabel *tl = [[UILabelalloc]init];//本地局部变量

        __weak UILabel *weakTL = tl;//弱引用变量

        

        NSLog(@"%s tl %p",__FUNCTION__ , &tl);

        NSLog(@"%s tl %@",__FUNCTION__ , tl);

        

        NSLog(@"%s weakTL %p",__FUNCTION__ , &weakTL);

        NSLog(@"%s weakTL %@",__FUNCTION__ , weakTL);

        

        void (^TestBlock)(void) = ^{


            //复制tl指针,并且强引用tl

            NSLog(@"%s tl %p",__FUNCTION__ , &tl);

            NSLog(@"%s tl %@",__FUNCTION__ , tl);

            

            //复制weakTL指针,并且弱引用weakTL

            NSLog(@"%s weakTL %p",__FUNCTION__ , &weakTL);

            NSLog(@"%s weakTL %@",__FUNCTION__ , weakTL);

        };

        

        tl = nil;

        

        TestBlock();

        

        NSLog(@"block is %@", TestBlock);

    }

    /*输出结果

     2014-02-21 17:50:42.591 TestBlock[13888:70b] -[ViewController testBlockWeakObj1] tl 0xbfffc9b0

     2014-02-21 17:50:42.591 TestBlock[13888:70b] -[ViewController testBlockWeakObj1] tl <UILabel: 0x8c57c30; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8c562d0>>

     2014-02-21 17:50:42.592 TestBlock[13888:70b] -[ViewController testBlockWeakObj1] weakTL 0xbfffc9ac

     2014-02-21 17:50:42.592 TestBlock[13888:70b] -[ViewController testBlockWeakObj1] weakTL <UILabel: 0x8c57c30; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8c562d0>>

     2014-02-21 17:50:42.592 TestBlock[13888:70b] __35-[ViewController testBlockWeakObj1]_block_invoke tl 0x8b09434

     2014-02-21 17:50:42.593 TestBlock[13888:70b] __35-[ViewController testBlockWeakObj1]_block_invoke tl <UILabel: 0x8c57c30; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8c562d0>>

     2014-02-21 17:50:42.611 TestBlock[13888:70b] __35-[ViewController testBlockWeakObj1]_block_invoke weakTL 0x8b09438

     2014-02-21 17:50:42.612 TestBlock[13888:70b] __35-[ViewController testBlockWeakObj1]_block_invoke weakTL <UILabel: 0x8c57c30; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8c562d0>>

     2014-02-21 17:50:42.612 TestBlock[13888:70b] block is <__NSMallocBlock__: 0x8b09420>

     */


    - (void)testBlockWeakObj2

    {

        __block UILabel *tl = [[UILabelalloc]init];//加上block关键字就变成全局变量

        __weak UILabel *weakTL = tl;//弱引用变量

        

        NSLog(@"%s tl %p",__FUNCTION__ , &tl);

        NSLog(@"%s tl %@",__FUNCTION__ , tl);

        

        NSLog(@"%s weakTL %p",__FUNCTION__ , &weakTL);

        NSLog(@"%s weakTL %@",__FUNCTION__ , weakTL);

        

        void (^TestBlock)(void) = ^{


            //tl是全局变量,强引用

            NSLog(@"%s tl %p",__FUNCTION__ , &tl);

            NSLog(@"%s tl %@",__FUNCTION__ , tl);

            

            //复制weakTL指针,并且弱引用weakTL

            NSLog(@"%s weakTL %p",__FUNCTION__ , &weakTL);

            NSLog(@"%s weakTL %@",__FUNCTION__ , weakTL);

        };

        

        tl = nil;

        

        TestBlock();

        

        NSLog(@"block is %@", TestBlock);

    }

    /*输出结果

     2014-02-21 17:55:13.832 TestBlock[13926:70b] -[ViewController testBlockWeakObj1] tl 0xbfffc9b0

     2014-02-21 17:55:13.832 TestBlock[13926:70b] -[ViewController testBlockWeakObj1] tl <UILabel: 0x8a32470; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8a37410>>

     2014-02-21 17:55:13.832 TestBlock[13926:70b] -[ViewController testBlockWeakObj1] weakTL 0xbfffc994

     2014-02-21 17:55:13.833 TestBlock[13926:70b] -[ViewController testBlockWeakObj1] weakTL <UILabel: 0x8a32470; frame = (0 0; 0 0); clipsToBounds = YES; userInteractionEnabled = NO; layer = <CALayer: 0x8a37410>>

     2014-02-21 17:55:13.833 TestBlock[13926:70b] __35-[ViewController testBlockWeakObj1]_block_invoke tl 0x8a3bdf8

     2014-02-21 17:55:13.833 TestBlock[13926:70b] __35-[ViewController testBlockWeakObj1]_block_invoke tl (null)

     2014-02-21 17:55:13.834 TestBlock[13926:70b] __35-[ViewController testBlockWeakObj1]_block_invoke weakTL 0x8a3bdd8

     2014-02-21 17:55:13.834 TestBlock[13926:70b] __35-[ViewController testBlockWeakObj1]_block_invoke weakTL (null)

     2014-02-21 17:55:13.834 TestBlock[13926:70b] block is <__NSMallocBlock__: 0x8a3bdc0>

     */


    版权声明:本文为博主原创文章,未经博主允许不得转载。

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  • 原文地址:https://www.cnblogs.com/zsw-1993/p/4879517.html
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