block定義
int (^addBlock)(int a,int b) = ^(int a,int b){
return a+b;
};
typedef常用block
typedef int (^SomeBlock)(BOOL flag,int value);
SomeBlock block = ^(BOOL flag,int value){
};
常用
//用來在塊內(nèi)修改變量
__block NSInteger count = 0;
//用來避免出現(xiàn)循環(huán)引用
__weak typeof (self) weakSelf = self;
//用來加強(qiáng)一下引用攻臀，避免weakSelf被釋放掉
__strong typeof (self) strongSelf = weakSelf;
