Objective-C 空Block用法

@interface Demo (){
void(^firstBlock)(); //局部变量
}
@end

//回调的block
^(void){
NSLog(@"---------------------------0");
}

typedef void (^Block)();  //定义block类型

//代码里的block变量
void(^firstBlock)() = ^(void) {
}
+ (NSDictionary *)dictWithTitle:(NSString *)title sel:(void(^)())sel; //函数里的代码块