textView 取消输入设置placeholder

最新推荐文章于 2024-10-16 10:41:12 发布

lisiben

最新推荐文章于 2024-10-16 10:41:12 发布

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分类专栏： iPhone iOS Objective-c 文章标签：移动开发

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本文介绍如何使用iOS中的UITextView实现自定义输入控制逻辑，例如禁止输入换行符并自动清除占位符文本。此外，还展示了如何设置UITextView的初始状态为占位符文本，并在用户开始编辑时自动隐藏占位符。

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- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {

if([text isEqualToString:@"\n"]) {
[textView resignFirstResponder];
return NO;
}

return YES;
}

- (BOOL)textView:(UITextView *)txtView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
if( [text rangeOfCharacterFromSet:[NSCharacterSet newlineCharacterSet]].location == NSNotFound ) {
return YES;
}

[txtView resignFirstResponder];
return NO;
}

- (void)textViewDidBeginEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@"placeholder text here..."]) {
textView.text = @"";
textView.textColor = [UIColor blackColor]; //optional
}
[textView becomeFirstResponder];
}

- (void)textViewDidEndEditing:(UITextView *)textView
{
if ([textView.text isEqualToString:@""]) {
textView.text = @"placeholder text here...";
textView.textColor = [UIColor lightGrayColor]; //optional
}
[textView resignFirstResponder];
}
just remember to set myUITextView with the exact text on creation e.g.

UITextView *myUITextView = [[UITextView alloc] init];
myUITextView.delegate = self;
myUITextView.text = @"placeholder text here...";
myUITextView.textColor = [UIColor lightGrayColor]; //optional
and make the parent class a UITextViewDelegate before including these methods e.g.

@interface MyClass () <UITextViewDelegate>
@end