Block的类型

在学习Block类型前，我们必须清楚内存的分布结构：

我们还需要把内存管理模式设置为MRC，在Build Phases -> Compile Sources中选中需要修改的文件，双击输入：-fno-objc-arc

Block的三种类型，分别是：

1. __NSGlobalBlock__：保存在Data区域；
2. __NSStackBlock__ ：保存在Stack区域；
3. __NSMallocBlock__：保存在Heap区域。

三种类型存在的关系，如下图：

__NSGlobalBlock__

// 1.在函数体外/方法外定义的Block
void (^outsideFunctionGlobalBlock)(void) = ^{
    NSLog(@"outside function global block");
};

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // 2. 在函数体内/方法内，不引用Block外的局部变量
        void (^insideFunctionGlobalBlock)(void) = ^{
            NSLog(@"inside function global block");
        };

        NSLog(@"outside = %@\ninside = %@", outsideFunctionGlobalBlock, insideFunctionGlobalBlock);
    }
    return 0;
}

__NSStackBlock__

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // 在block内引用了外部的局部变量
        int a = 10;
        void (^stackBlock)(void) = ^{
            NSLog(@"stack block:%d", a);
        };

        NSLog(@"stackBlock = %@", stackBlock);
    }
    return 0;
}

__NSMallocBlock__

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // 由stack类型的block使用copy得来
        int a = 10;
        void (^heapBlock)(void) = [^{
            NSLog(@"stack block:%d", a);
        } copy];
        NSLog(@"heapBlock = %@", heapBlock);
        }
    return 0;
}

思考

请回答下面代码中Block的类型：

int a = 10;

void (^outsideFunctionBlock1)(void) = ^{
    NSLog(@"outside function block：%d", a);
};

void (^outsideFunctionBlock2)(int x, int y) = ^(int x, int y){
    NSLog(@"outside function block：%d, (x+y = %d)", a, x+y);
};

int main(int argc, const char * argv[]) {
    @autoreleasepool {

        static int num = 20;

        int var = 30;

        void (^insideFunctionBlock1)(void) = ^{
            NSLog(@"inside function block：%d", a);
        };

        void (^insideFunctionBlock2)(void) = ^{
            NSLog(@"inside function block：%d", var);
        };

        void (^insideFunctionBlock3)(void) = ^{
            NSLog(@"inside function block：%d，num = %d", a, num);
        };  

        void (^insideFunctionBlock4)(void) = ^{
            NSLog(@"inside function block：%d, num = %d, var = %d", a, num, var);
        };        

        void (^insideFunctionBlock5)(void) = [insideFunctionBlock1 copy];

        void (^insideFunctionBlock6)(void) = [insideFunctionBlock2 copy];

        void (^insideFunctionBlock7)(void) = [insideFunctionBlock3 copy];

    }
    return 0;
}