一: 定义block 初始化
#import <UIKit/UIKit.h>
@interface LHQDemoView : UIView
- (instancetype)initWithFrame:(CGRect)frame andCompelete:(void(^)(NSString *msg))block;
- (instancetype)initWithFrame:(CGRect)frame andCompelete:(void(^)(NSString *msg))block{
if(self = [super initWithFrame:frame]){
UIButton *btn = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, 50, 50)];
[btn setTitle:@"提示" forState:UIControlStateNormal];
[btn addTarget:self action:@selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];
[self addSubview:btn];
self.block = block;
}
return self;
}
二: 定义全局block
@interface LHQDemoView()
//block定义的时候一定要用copy
/*
block默认在栈中 栈中内存归系统管理
系统管理有个弊端:到作用于结束就被干掉
执行了一个copy操作之后,就会把block从栈中放到堆中
会自动有一个强引用来指向它
*/
@property(nonatomic,copy)void(^block)(NSString *);
设置
self.block = block;
三: 给block赋值
- (void)btnClicked: (UIButton *)btn{
self.block(@"点击了某个按钮");
NSLog(@"btnClicked");
}
四: 使用
导入头文件
#import "LHQDemoView.h"
@interface ViewController ()
@end
LHQDemoView *demoView = [[LHQDemoView alloc]initWithFrame:CGRectMake(100, 200, 100, 100) andCompelete:^(NSString *msg) {
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"温馨提示" message:msg delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:nil, nil];
[alert show];
}];
[self.view addSubview:demoView];