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目標效果: 在限制文本輸入長度的時候, 輸入漢字可以正常輸入最長限度
目標效果 -
在iOS開發中, 經常有輸入框輸入內容長度限制的需求, 如果我們只判斷輸入框文本長度, 然后進行切割, 那么就會在輸入漢字時無法正常輸入全部長度的漢字, 如下圖
13.gif 代碼如下
if (self.text.length > 10) {
self.text = [self.text substringToIndex:10];
}
上述代碼雖然也做到了對輸入內容進行長度限制, 但是在輸入中文時的體驗并不是很好, 因為最后的幾個字如果拼音較長就很難輸入
- 所以我們需要對限制長度的代碼進行優化, 讓用戶在輸入漢字時, 可以完整便捷的輸入最大長度的漢字, 就如最上方目標效果一樣
- 優化代碼如下:
NSString *InputMethodType = [[UIApplication sharedApplication]textInputMode].primaryLanguage;
// 如果當前輸入法為漢語輸入法
if ([InputMethodType isEqualToString:@"zh-Hans"]) {
// 獲取標記部分
UITextRange *selectedRange = [self markedTextRange];
//獲取標記部分, 此部分為用戶未決定輸入部分
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];
// 當沒有標記部分時截取字符串
if (position == nil) {
if (self.text.length > 10) {
self.text = [self.text substringToIndex:10];
}
}
}else {
if (self.text.length > 10) {
self.text = [self.text substringToIndex:10];
}
}
- 下面是我寫的分類代碼, 可以在項目中直接使用
- .h文件代碼
//
// UITextField+LTExtension.h
// LTTextField
//
// Created by 冰凌天 on 2017/7/6.
// Copyright ? 2017年 冰凌天. All rights reserved.
//
#import <UIKit/UIKit.h>
@interface UITextField (LTExtension)
/** 最大輸入長度 */
@property (nonatomic, assign) NSInteger maxInputLenght;
@end
- .m文件代碼
//
// UITextField+LTExtension.m
// LTTextField
//
// Created by 冰凌天 on 2017/7/6.
// Copyright ? 2017年 冰凌天. All rights reserved.
//
#import "UITextField+LTExtension.h"
#import <objc/runtime.h>
static NSString *maxInputLenghtKey = @"maxInputLenghtKey";
@interface UITextField ()
/** 是否已經設置過最大值 */
@property (nonatomic, assign) NSInteger isSetupMaxInputLenght;
@end
@implementation UITextField (LTExtension)
#pragma mark - < 方法交換 >
+ (void)load
{
Method dealloc = class_getInstanceMethod(self, NSSelectorFromString(@"dealloc"));
Method lt_dealloc = class_getInstanceMethod(self, @selector(lt_dealloc));
method_exchangeImplementations(dealloc, lt_dealloc);
Method initWithFrame = class_getInstanceMethod(self, NSSelectorFromString(@"initWithFrame:"));
Method lt_initWithFrame = class_getInstanceMethod(self, @selector(lt_initWithFrame:));
method_exchangeImplementations(initWithFrame, lt_initWithFrame);
Method initWithCoder = class_getInstanceMethod(self, NSSelectorFromString(@"initWithCoder:"));
Method lt_initWithCoder = class_getInstanceMethod(self, @selector(lt_initWithCoder:));
method_exchangeImplementations(initWithCoder, lt_initWithCoder);
}
- (void)lt_dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
[self lt_dealloc];
}
- (instancetype)lt_initWithFrame:(CGRect)frame
{
[self lt_initWithFrame:frame];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(lt_category_maxInputLenght_textDidChangeNotification:) name:UITextFieldTextDidChangeNotification object:nil];
return self;
}
- (instancetype)lt_initWithCoder:(NSCoder *)coder
{
[self lt_initWithCoder:coder];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(lt_category_maxInputLenght_textDidChangeNotification:) name:UITextFieldTextDidChangeNotification object:nil];
return self;
}
#pragma mark - < 屬性綁定 >
- (void)setMaxInputLenght:(NSInteger)maxInputLenght
{
objc_setAssociatedObject(self, (__bridge const void *)(maxInputLenghtKey), @(maxInputLenght), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSInteger)maxInputLenght
{
NSNumber *maxInputLenght = objc_getAssociatedObject(self, (__bridge const void *)(maxInputLenghtKey));
return maxInputLenght.integerValue;
}
#pragma mark - < 輸入框內容處理 >
- (void)lt_category_maxInputLenght_textDidChangeNotification:(NSNotification *)notification
{
if (self.maxInputLenght <= 0) return;
NSString *InputMethodType = [[UIApplication sharedApplication]textInputMode].primaryLanguage;
// 如果當前輸入法為漢語輸入法
if ([InputMethodType isEqualToString:@"zh-Hans"]) {
// 獲取標記部分
UITextRange *selectedRange = [self markedTextRange];
//獲取標記部分, 此部分為用戶未決定輸入部分
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];
// 當沒有標記部分時截取字符串
if (position == nil) {
if (self.text.length > self.maxInputLenght) {
self.text = [self.text substringToIndex:self.maxInputLenght];
}
}
}else {
if (self.text.length > self.maxInputLenght) {
self.text = [self.text substringToIndex:self.maxInputLenght];
}
}
}
@end
Swift版本
import UIKit
class LTTextField: UITextField {
var maxInputlength = 0
override var text: String? {
didSet {
self.textDidChange()
}
}
override init(frame: CGRect) {
super.init(frame: frame)
NotificationCenter.default.addObserver(self, selector: #selector(textDidChange), name: NSNotification.Name.UITextFieldTextDidChange, object: nil)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
@objc fileprivate func textDidChange() {
if maxInputlength <= 0 {
return
}
let inputMethodType : String = UIApplication.shared.textInputMode?.primaryLanguage ?? ""
if inputMethodType == "zh-Hans" {
if let selectedRange = markedTextRange {
let p = position(from: selectedRange.start, offset: 0)
if p == nil {
if (text?.characters.count ?? 0) > maxInputlength {
text = (text! as NSString).substring(to: maxInputlength)
}
}
}else {
if (text?.characters.count ?? 0) > maxInputlength {
text = (text! as NSString).substring(to: maxInputlength)
}
}
}else {
if (text?.characters.count ?? 0) > maxInputlength {
text = (text! as NSString).substring(to: maxInputlength)
}
}
}
deinit {
NotificationCenter.default.removeObserver(self)
}
}
- 最后: 上面的內容如果有錯誤或者可優化的地方請留言, 我會進行修改
