Block与参数

void(^block1)();
void(^block2)(void);

#import "ViewController.h"

typedef NS_ENUM(NSUInteger, DataType) {
    DataTypeWithoutMessage = 0,
    DataTypeWithMessage,
};

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.view.backgroundColor = [UIColor whiteColor];
    
    [self processDataForType:DataTypeWithoutMessage block:^void(NSUInteger code) {
        // code = 100
        NSLog(@"code = %tu", code);
    }];
    
    [self processDataForType:DataTypeWithoutMessage block:^void(NSUInteger code, NSString *message) {
        // code = 100, message = (null)
        NSLog(@"code = %tu, message = %@", code, message);
    }];
    
    [self processDataForType:DataTypeWithMessage block:^void(NSUInteger code, NSString *message) {
        // code = 200, message = Hello World
        NSLog(@"code = %tu, message = %@", code, message);
    }];
}

// 第二个参数block，其类型为void(^)()，圆括号中没有void，并不表示该block没有参数，而是表示该block为可变参数
- (void)processDataForType:(DataType)dataType block:(void(^)())block {
    switch (dataType) {
        case DataTypeWithoutMessage:
            !block ?: block(100);
            break;
        case DataTypeWithMessage:
            !block ?: block(200, @"Hello World");
            break;
        default:
            break;
    }
}

@end