监听textfield输入内容

[UITextField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];

#import "ViewController.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet UITextField *textF;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.textF addTarget:self action:@selector(hehe:) forControlEvents:UIControlEventEditingChanged];
}

- (void)hehe:(UITextField *)tf{
    NSString *str = tf.text;
    NSLog(@"%@",str);
}

@end