IOS TextView content is empty when the Set button is not available

Sometimes doing projects will encounter a requirement: When a textview content is empty, the Set button is not available, the specific implementation is as follows:

1. The button is initially set to not available:

self.customButton.enabled = NO;

2. Through the agent or notification monitoring TextView text content change state, through the HasText method to determine whether there is text content in the TextView to set the button state:

Agent:

Compliance Agreement:

@interface Customviewcontroller () <UITextViewDelegate>

To set up a proxy:

Self.textview. delegate = self;

To implement the Proxy method:

-(void) Textviewdidchange: (Uitextview *) textview{    = textview.hastext; }

Notice:

Set notification listeners and objects:

object: Self.textview];

To implement the notification method:

-(void) textdidchanged{self    .  CustomButton= self.textView.hasText;}

To remove a notification listener:

-(void) dealloc{    [[Nsnotificationcenter Defaultcenter] removeobserver:self];}

IOS TextView content is empty when the Set button is not available