当我加载一个UIView时,我如何在iPhone SDK上设置UITextField的最大字符数?
当前回答
使用这段代码在这里RESTRICTED_LENGTH是长度你想限制的文本字段。
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if (textField == nameTF) {
int limit = RESTRICTED_LENGTH - 1;
return !([textField.text length]>limit && [string length] > range.length);
}
else
{
return YES;
}
return NO;
}
其他回答
通常您有多个长度不同的输入字段。
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
int allowedLength;
switch(textField.tag) {
case 1:
allowedLength = MAXLENGTHNAME; // triggered for input fields with tag = 1
break;
case 2:
allowedLength = MAXLENGTHADDRESS; // triggered for input fields with tag = 2
break;
default:
allowedLength = MAXLENGTHDEFAULT; // length default when no tag (=0) value =255
break;
}
if (textField.text.length >= allowedLength && range.length == 0) {
return NO; // Change not allowed
} else {
return YES; // Change allowed
}
}
稍微超出了回答原来的问题,并扩展了Frouo的答案,这里有扩展来修剪空白字符串和最大长度,并利用这些字符串扩展来修剪UITextField到最大长度:
// In String_Extensions.swift
extension String {
func trimmedString() -> String {
var trimmedString = self.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
let components = trimmedString.componentsSeparatedByCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet()).filter { count($0) > 0 }
return " ".join(components)
}
func trimmedStringToMaxLength(maxLength: Int) -> String {
return trimmedString().substringToIndex(advance(startIndex, min(count(self), maxLength))).trimmedString()
}
}
// In UITextField_Extensions.swift
private var maxLengthDictionary = [UITextField : Int]()
private var textFieldMaxLength = 20
extension UITextField {
@IBInspectable var maxLength: Int {
get {
if let maxLength = maxLengthDictionary[self] {
return maxLength
} else {
return textFieldMaxLength
}
}
set {
maxLengthDictionary[self] = newValue < textFieldMaxLength + 1 ? newValue : textFieldMaxLength
}
}
func trimAndLimitToMaxLength() {
text = text.trimmedStringToMaxLength(maxLength)
}
}
let someTextField = UITextField()
let someString = " This is a string that is longer than allowable for a text field. "
someTextField.text = someString
someTextField.trimAndLimitToMaxLength()
println(someTextField.text) // Prints "This is a string tha"
let anotherTextField = UITextField()
anotherTextField.maxLength = 5
anotherTextField.text = someString
anotherTextField.trimAndLimitToMaxLength()
println(anotherTextField.text) // Prints "This"
trimAndLimitToMaxLength() could be used in UITextFieldDelegate's textFieldDidEndEditing(_:) so that a user could enter or paste in a longer than acceptable string and then shorten it vs. just cutting off the input at the max length. In doing this, I would also set attributed text styles to indicate any portion of the text that goes beyond the acceptable length (e.g., [NSBackgroundColorAttributeName : UIColor.redColor(), NSForegroundColorAttributeName : UIColor.whiteColor(), NSStrikethroughStyleAttributeName : NSNumber(int: 1)]
Swift 2.1+
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if (range.length + range.location > textField.text!.characters.count )
{
return false;
}
let newLength = textField.text!.characters.count + string.characters.count - range.length
return newLength <= 25
}
希望能有所帮助
快速2.0 +
首先,为这个过程创建一个类。我们称之为StringValidator.swift。
然后把下面的代码粘贴进去。
import Foundation
extension String {
func containsCharactersIn(matchCharacters: String) -> Bool {
let characterSet = NSCharacterSet(charactersInString: matchCharacters)
return self.rangeOfCharacterFromSet(characterSet) != nil
}
func containsOnlyCharactersIn(matchCharacters: String) -> Bool {
let disallowedCharacterSet = NSCharacterSet(charactersInString: matchCharacters).invertedSet
return self.rangeOfCharacterFromSet(disallowedCharacterSet) == nil
}
func doesNotContainCharactersIn(matchCharacters: String) -> Bool {
let characterSet = NSCharacterSet(charactersInString: matchCharacters)
return self.rangeOfCharacterFromSet(characterSet) == nil
}
func isNumeric() -> Bool
{
let scanner = NSScanner(string: self)
scanner.locale = NSLocale.currentLocale()
return scanner.scanDecimal(nil) && scanner.atEnd
}
}
现在保存类.....
使用. .
现在转到你的viewController.swift类,并将你的文本字段的outlet设为..
@IBOutlet weak var contactEntryTxtFld: UITextField! //First textfield
@IBOutlet weak var contactEntryTxtFld2: UITextField! //Second textfield
现在转到textfield的shouldChangeCharactersInRange方法,像下面这样使用。
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {
if string.characters.count == 0 {
return true
}
let latestText = textField.text ?? ""
let checkAbleText = (latestText as NSString).stringByReplacingCharactersInRange(range, withString: string)
switch textField {
case contactEntryTxtFld:
return checkAbleText.containsOnlyCharactersIn("0123456789") && prospectiveText.characters.count <= 5
case contactEntryTxtFld2:
return checkAbleText.containsOnlyCharactersIn("0123456789") && prospectiveText.characters.count <= 5
default:
return true
}
}
不要忘记设置文本字段的委托协议/方法。
让我来解释一下……我正在使用我在另一个类中写的字符串的简单扩展过程。现在我只是调用那些扩展方法从另一个类,我需要他们通过添加检查和最大值。
功能……
它将设置特定文本字段的最大限制。 它将为特定文本字段设置接受的键的类型。
类型……
containsOnlyCharactersIn //只接受字符。
containsCharactersIn //接受字符组合
doesNotContainsCharactersIn //不接受字符
希望这对你有所帮助.... 谢谢. .
使用下面的扩展来设置UITextField和UITextView的最大字符长度。
斯威夫特4.0
private var kAssociationKeyMaxLength: Int = 0
private var kAssociationKeyMaxLengthTextView: Int = 0
extension UITextField {
@IBInspectable var maxLength: Int {
get {
if let length = objc_getAssociatedObject(self, &kAssociationKeyMaxLength) as? Int {
return length
} else {
return Int.max
}
}
set {
objc_setAssociatedObject(self, &kAssociationKeyMaxLength, newValue, .OBJC_ASSOCIATION_RETAIN)
addTarget(self, action: #selector(checkMaxLength), for: .editingChanged)
}
}
@objc func checkMaxLength(textField: UITextField) {
guard let prospectiveText = self.text,
prospectiveText.count > maxLength
else {
return
}
let selection = selectedTextRange
let indexEndOfText = prospectiveText.index(prospectiveText.startIndex, offsetBy: maxLength)
let substring = prospectiveText[..<indexEndOfText]
text = String(substring)
selectedTextRange = selection
}
}
UITextView
extension UITextView:UITextViewDelegate {
@IBInspectable var maxLength: Int {
get {
if let length = objc_getAssociatedObject(self, &kAssociationKeyMaxLengthTextView) as? Int {
return length
} else {
return Int.max
}
}
set {
self.delegate = self
objc_setAssociatedObject(self, &kAssociationKeyMaxLengthTextView, newValue, .OBJC_ASSOCIATION_RETAIN)
}
}
public func textViewDidChange(_ textView: UITextView) {
checkMaxLength(textField: self)
}
@objc func checkMaxLength(textField: UITextView) {
guard let prospectiveText = self.text,
prospectiveText.count > maxLength
else {
return
}
let selection = selectedTextRange
let indexEndOfText = prospectiveText.index(prospectiveText.startIndex, offsetBy: maxLength)
let substring = prospectiveText[..<indexEndOfText]
text = String(substring)
selectedTextRange = selection
}
}
你可以在下面设置限制。
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