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
让我们简单点
创建一个UILabel并把它放在你的文本视图上(给文本作为占位符-设置颜色为灰色-你可以在你的xib中做这一切) 现在在头文件中声明UILabel和textviewDelegate 现在你可以简单地隐藏标签,当你点击textview
完整代码如下
头
@interface ViewController :UIViewController<UITextViewDelegate>{
}
@property (nonatomic,strong) IBOutlet UILabel *PlceHolder_label;
@property (nonatomic,strong) IBOutlet UITextView *TextView;
@end
实现
@implementation UploadFoodImageViewController
@synthesize PlceHolder_label,TextView;
- (void)viewDidLoad
{
[super viewDidLoad];
}
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView{
if([textView isEqual:TextView]){
[PlceHolder_label setHidden:YES];
[self.tabScrlVw setContentOffset:CGPointMake(0,150) animated:YES];
}
return YES;
}
@end
别忘了连接textView和UILabel文件所有者从xib
其他回答
如果你正在寻找一个简单的方法来实现这一点,试试我的方法:
- (BOOL)textViewShouldBeginEditing:(UITextView *)textView
{
if ([[textView text] isEqualToString:PLACE_HOLDER_TEXT]) {
textView.text = @"";
textView.textColor = [UIColor blackColor];
}
return YES;
}
-(BOOL)textViewShouldEndEditing:(UITextView *)textView
{
if ([[textView text] length] == 0) {
textView.text = PLACE_HOLDER_TEXT;
textView.textColor = [UIColor lightGrayColor];
}
return YES;
}
是的,就是它PLACE_HOLDER_TEXT是一个NSString包含你的占位符
这里还有另一种方法,它复制了UITextField占位符的轻微缩进:
将UITextField拖到UITextView的右边,这样它们的左上角就对齐了。将占位符文本添加到文本字段。
在viewDidLoad中添加:
[tView setDelegate:self];
tView.contentInset = UIEdgeInsetsMake(-8,-8,0,0);
tView.backgroundColor = [UIColor clearColor];
然后添加:
- (void)textViewDidChange:(UITextView *)textView {
if (textView.text.length == 0) {
textView.backgroundColor = [UIColor clearColor];
} else {
textView.backgroundColor = [UIColor whiteColor];
}
}
这完美地模仿了UITextField的占位符,其中占位符文本一直保留到您实际键入一些内容为止。
private let placeholder = "Type here"
@IBOutlet weak var textView: UITextView! {
didSet {
textView.textColor = UIColor.lightGray
textView.text = placeholder
textView.selectedRange = NSRange(location: 0, length: 0)
}
}
extension ViewController: UITextViewDelegate {
func textViewDidChangeSelection(_ textView: UITextView) {
// Move cursor to beginning on first tap
if textView.text == placeholder {
textView.selectedRange = NSRange(location: 0, length: 0)
}
}
func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
if textView.text == placeholder && !text.isEmpty {
textView.text = nil
textView.textColor = UIColor.black
textView.selectedRange = NSRange(location: 0, length: 0)
}
return true
}
func textViewDidChange(_ textView: UITextView) {
if textView.text.isEmpty {
textView.textColor = UIColor.lightGray
textView.text = placeholder
}
}
}
我创建了一个实例变量来检查是否显示占位符:
BOOL showPlaceHolder;
UITextView * textView; // and also the textView
在viewDidLoad上设置:
[self setPlaceHolder];
下面是它的作用:
- (void)setPlaceholder
{
textView.text = NSLocalizedString(@"Type your question here", @"placeholder");
textView.textColor = [UIColor lightGrayColor];
self.showPlaceHolder = YES; //we save the state so it won't disappear in case you want to re-edit it
}
我还创建了一个按钮来退出键盘。您不必这样做,但这里很酷的事情是,如果没有输入任何内容,占位符将再次显示
- (void)textViewDidBeginEditing:(UITextView *)txtView
{
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Done" style:UIBarButtonItemStyleDone target:self action:@selector(resignKeyboard)];
if (self.showPlaceHolder == YES)
{
textView.textColor = [UIColor blackColor];
textView.text = @"";
self.showPlaceHolder = NO;
}
}
- (void)resignKeyboard
{
[textView resignFirstResponder];
//here if you created a button like I did to resign the keyboard, you should hide it
if (textView.text.length == 0) {
[self setPlaceholder];
}
}
我遵循了这个链接的代码。只有7个简单的步骤。它添加了一个UILabel的textView和隐藏/显示标签时,文本输入或从textView通过textView的textViewDidChangeSelection(_ textView: UITextView)委托方法。我将步骤放在代码上方的注释中。
// 1. make sure to include the UITextViewDelegate
class YourClass: UITextViewDelegate {
@IBOutlet weak var textView : UITextView!
// 2. create placeholder textLabel
let placeHolderTextLabel: UILabel = {
let placeholderLabel = UILabel()
placeholderLabel.text = "Placeholder text..."
placeholderLabel.sizeToFit()
placeholderLabel.textColor = UIColor.lightGray
return placeholderLabel
}()
override func viewDidLoad() {
super.viewDidLoad()
// 3. set textView delegate
textView.delegate = self
configurePlaceholderTextLabel()
}
func configurePlaceholderTextLabel() {
// 4. add placeholder label to textView, set it's frame and font
textView.addSubview(placeHolderTextLabel)
placeHolderTextLabel.frame.origin = CGPoint(x: 5, y: (textView.font?.pointSize)! / 2)
placeHolderTextLabel.font = UIFont.systemFont(ofSize: (textView.font?.pointSize)!)
// 5. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView
placeHolderTextLabel.isHidden = !textView.text.isEmpty
}
// 6. implement textView delegate method to update the placeHolderTextLabel when the text is changed
func textViewDidChangeSelection(_ textView: UITextView) {
// 7. decide wether the placeHolderTextLabel is hidden or not depending on if there is or isn't text inside the textView when text in textView is changed
placeHolderTextLabel.isHidden = !textView.text.isEmpty
}
}