block三种类型区分

2019-03-03 本文已影响0人介和

参考 https://blog.csdn.net/Deft_MKJing/article/details/53165799

int a = 1;

// 这里的^{}初始化的block赋值给block变量，在OC中没有具体写明的情况下应该就是strong类型的，这就是上面第三点的例子

// 打印出来 first <__NSMallocBlock__: 0x60800004d290>

void (^block)(void) = ^{

NSLog(@"%d",a);

};

NSLog(@"first %@",block);

// 没有截获变量的时候就是globalBlock

// second<__NSGlobalBlock__: 0x102f80100>

NSLog(@"second%@",^{NSLog(@"呵呵");});

// 截获了变量就是stackBlock

// third<__NSStackBlock__: 0x7fff5cc7faa0>

NSLog(@"third%@",^{NSLog(@"%d",a);});

__block int val = 10;

__strong blk strongPointerBlock = ^{NSLog(@"val1 = %d", ++val);};

// strongPointerBlock: <__NSMallocBlock__: 0x600000044e90>

NSLog(@"strongPointerBlock: %@", strongPointerBlock); //1

__weak blk weakPointerBlock = ^{NSLog(@"val2 = %d", ++val);};

// weakPointerBlock: <__NSStackBlock__: 0x7fff5282ea70>

NSLog(@"weakPointerBlock: %@", weakPointerBlock); //2

// mallocBlock3: <__NSMallocBlock__: 0x608000046930>

NSLog(@"mallocBlock3: %@", [weakPointerBlock copy]); //3

// 截获了test <__NSStackBlock__: 0x7fff5282ea48>

NSLog(@"test4 %@", ^{NSLog(@"val4 = %d", ++val);}); //4

// test5 <__NSMallocBlock__: 0x60800005c0b0>

NSLog(@"test5 %@", [^{NSLog(@"val4 = %d", ++val);} copy]); //5

// stackBlock经过传参打印

NSLog(@"传参后 %@",[self getBlock]);

}

- (blk)getBlock

{

int val = 11;

// 上面已经介绍了，这种直接打印传参前的block，应该是__NSStackBlock__

NSLog(@"传参前：%@",^{NSLog(@"%d",val);});

// 那么现在我们直接传出去

return ^{NSLog(@"%d",val);};

}