我的应用程序使用UITextView。现在我想让UITextView有一个占位符,类似于你可以为UITextField设置的占位符。
如何做到这一点?
我的应用程序使用UITextView。现在我想让UITextView有一个占位符,类似于你可以为UITextField设置的占位符。
如何做到这一点?
当前回答
在看完所有答案后,我意识到我需要一些简单的,同时可重用的东西,这样我就可以在我的项目中为所有uitextview添加相同的功能。最后我得到了以下代码:
extension UITextView {
// MARK: TextView PlaceHolderLabel Setup
func createPlaceHolderLabel(with text: String) {
let lbl = UILabel()
self.addSubview(lbl)
// Add your constraints here
lbl.text = text
lbl.textColor = .lightGray
}
// My Textview contains only one UILabel, and for my use case the below code works, tweak it according to your use case
// Lastly two methods to toggle between show and hide the placeholder label
func hidePlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = true
}
func showPlaceHolderLabel() {
guard let lbl = self.subviews.first(where: { $0 is UILabel }) else { return }
lbl.isHidden = false
}
}
当UILabel作为子视图添加到UITextView时,textView游标位置和UILabel位置将不匹配,因此在占位符文本之前留下一个空间
class ViewController: UIViewController, UITextViewDelegate {
var textView: UITextView!
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(textView)
// Also setup textView constraints as per your need
// Add placeholder to your textView
// Leave one space before placeholder string
textView.createPlaceHolderLabel(with: " Address")
textView.delegate = self
}
然后在textViewdidChange方法中添加以下代码
func textViewDidChange(_ textView: UITextView) {
if textView.text.isEmpty {
textView.showPlaceHolderLabel()
} else {
textView.hidePlaceHolderLabel()
}
}
它可以在所有uitextview中重用。
其他回答
更简单,并且仍然考虑到用户在某些时候输入的一些文本
BOOL placeHolderTextVisible;
在viewDidLoad上,设置它为YES(或DidMoveToSuperview,或awakeFromNib)
然后,在 - (BOOL) textView:(UITextView*)textView shouldBeginEditing
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView;
{
if (placeHolderTextVisible) {
placeHolderTextVisible = NO;
textView.text = @"";
}
return YES;
}
我能够做添加一个“占位符”到UITextView与很多少的代码。这就是我所做的:
UITextView *textView = [[UITextView alloc] initWithFrame:CGRectMake(60, 800, 200, 60)];
textView.text = @"Write characters here...";
textView.textColor=[UIColor grayColor];
textView.font = [UIFont fontWithName:@"Hevlatica" size:15];
textView.delegate=self;
我猜这不是一个真正的占位符,因为你必须在写之前删除文本,但如果你想要一些更简单的东西,它可能会有帮助。
一个更简单的方法是创建一个次要的UITextView,它具有与原始文本视图相同的所有属性,除了不同的textColor,并带有约束以确保它们保持对齐。然后当任何字符进入主文本视图时,隐藏克隆文本视图,否则显示带有一些文本的克隆文本视图。
这可以通过几种方式实现,但相对简单的方法是子类化UITextView并将所有这些逻辑保留在子类中。
所以,子类UITextView并允许它惰性地创建它的占位符视图
接口文件:
@interface FOOTextView : UITextView <UITextViewDelegate>
@property (nonatomic, copy) NSString *placeholderText;
- (void)checkPlaceholder;
@end
实现文件:
#import "FOOTextView.h"
@interface FOOTextView ()
@property (nonatomic, strong) UITextView *placeholderTextView;
@end
@implementation FOOTextView
- (void)checkPlaceholder {
// Hide the placeholder text view if we've got any text
self.placeholderTextView.hidden = (self.text.length > 0 || self.attributedText.length > 0);
}
- (void)setPlaceholderText:(NSString *)placeholderText {
_placeholderText = [placeholderText copy];
// Setup the placeholder text view if we haven't already
[self setupPlaceholderTextView];
// Apply the placeholder text to the placeholder text view
self.placeholderTextView.text = placeholderText;
}
- (void)setupPlaceholderTextView {
if (!self.placeholderTextView) {
// Setup the place holder text view, duplicating our visual setup
self.placeholderTextView = [[UITextView alloc] initWithFrame:CGRectZero];
self.placeholderTextView.translatesAutoresizingMaskIntoConstraints = NO;
self.placeholderTextView.textColor = self.placeholderTextColor ? self.placeholderTextColor : [UIColor colorWithRed:199.f/255.f green:199.f/255.f blue:205.f/255.f alpha:1.f];
self.placeholderTextView.userInteractionEnabled = NO;
self.placeholderTextView.font = self.font;
self.placeholderTextView.textAlignment = self.textAlignment;
self.placeholderTextView.backgroundColor = self.backgroundColor;
self.placeholderTextView.editable = NO;
// Our background color must be clear for the placeholder text view to show through
self.backgroundColor = [UIColor clearColor];
// Insert the placeholder text view into our superview, below ourself so it shows through
[self.superview insertSubview:self.placeholderTextView belowSubview:self];
// Setup constraints to ensure the placeholder text view stays aligned with us
NSLayoutConstraint *constraintCenterX = [NSLayoutConstraint constraintWithItem:self.placeholderTextView attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterX multiplier:1.f constant:0.f];
NSLayoutConstraint *constraintCenterY = [NSLayoutConstraint constraintWithItem:self.placeholderTextView attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterY multiplier:1.f constant:0.f];
NSLayoutConstraint *constraintWidth = [NSLayoutConstraint constraintWithItem:self.placeholderTextView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeWidth multiplier:1.f constant:0.f];
NSLayoutConstraint *constraintHeight = [NSLayoutConstraint constraintWithItem:self.placeholderTextView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeHeight multiplier:1.f constant:0.f];
NSArray *constraints = @[constraintCenterX, constraintCenterY, constraintWidth, constraintHeight];
[self.superview addConstraints:constraints];
}
}
- (void)setPlaceholderTextColor:(UIColor *)placeholderTextColor {
_placeholderTextColor = placeholderTextColor;
self.placeholderTextView.textColor = _placeholderTextColor;
}
- (void)setBackgroundColor:(UIColor *)backgroundColor {
// We don't want a background color ourselves, instead we want our placeholder text view to have the desired background color
[self.placeholderTextView setBackgroundColor:backgroundColor];
}
- (void)removeFromSuperview {
// Ensure we also remove our placeholder text view
[self.placeholderTextView removeFromSuperview];
self.placeholderTextView = nil;
[super removeFromSuperview];
}
#pragma mark - Text View Delegation
- (void)textViewDidChange:(UITextView *)textView {
[self checkPlaceholder];
}
@end
使用上面的类,如果你设置了一个FOOTextView的委托实例到它自己,一切都将开箱工作:
FOOTextView *myTextView = ...
myTextView.placeholderText = @"What's on your mind?";
myTextView.placeholderTextColor = [UIColor lightGrayColor];
myTextView.delegate = myTextView;
如果你想另一个对象接管作为委托,那么你只需要在textViewDidChange: delegate方法中调用文本视图的checkPlaceholder方法,例如;
FOOTextView *myTextView = ...
myTextView.placeholderText = @"What's on your mind?";
myTextView.placeholderTextColor = [UIColor lightGrayColor];
myTextView.delegate = self;
self.myTextView = myTextView;
- (void)textViewDidChange:(UITextView *)textView {
// Call the checkPlaceholder method to update the visuals
[self.myTextView checkPlaceholder];
}
在尝试了一些建议的方法后,我写了一个更清晰的实现,并将其发布到Github上。拉请求和问题是欢迎的。
与其他方法相比,这里提出了一些关键的改进:
不会在drawRect:中分配一个UILabel。(请不要这样做。) 不将文本视图的当前文本与所需的占位符进行比较以交换颜色。 当听写处于活动状态时隐藏占位符(如UITextField)。
在h课上
@interface RateCommentViewController : UIViewController<UITextViewDelegate>{IBoutlet UITextview *commentTxtView;}
在。m类
- (void)viewDidLoad{
commentTxtView.text = @"Comment";
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.delegate = self;
}
- (BOOL) textViewShouldBeginEditing:(UITextView *)textView
{
commentTxtView.text = @"";
commentTxtView.textColor = [UIColor blackColor];
return YES;
}
-(void) textViewDidChange:(UITextView *)textView
{
if(commentTxtView.text.length == 0){
commentTxtView.textColor = [UIColor lightGrayColor];
commentTxtView.text = @"Comment";
[commentTxtView resignFirstResponder];
}
}