在block内部更改外部的变量

开发调优
1 
#import <Foundation/Foundation.h>
void myBLock() {
    __block int num = 5;
    void (^myBlockInternal)(void) = ^{
        num = 6;
        NSLog(@"%d", num);
    };
    myBlockInternal();
}

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        myBLock();
    }
    return 0;
}

输出

2018-08-13 12:00:14.264296+0800 Block[43795:1488802] 6
2018-08-13 12:00:14.264494+0800 Block[43795:1488802] Hello, World!
Program ended with exit code: 0