1、在第二个视图控制器的.h文件中定义声明Block属性：
// 定义block
@property (nonatomic, copy) void (^NextViewControllerBlock)(NSString *tfText);
@interface NextViewController ()
@property (weak, nonatomic) IBOutlet UITextField *inputTF;
@end
- (IBAction)BtnAction:(id)sender {
// 判断block是否为空
if (self.NextViewControllerBlock) {
self.NextViewControllerBlock(self.inputTF.text);
}
[self.navigationController popViewControllerAnimated:YES];
}
2、在第一个视图中获得第二个视图控制器，并且用第二个视图控制器来调用定义的属性：
@interface AViewController ()
@property (weak, nonatomic) IBOutlet UILabel *nextVCInfoLabel;
@end
- (IBAction)btnClicked:(id)sender {
NextViewController*nextVC = [[NextViewController alloc]init]; nextVC.NextViewControllerBlock= ^(NSString *tfText) {
self.nextVCInfoLabel.text = tfText;
};
[self.navigationController pushViewController:nextVC animated:YES];
}
原文地址：https://www.cnblogs.com/xuzb/p/8677738.html