需求: 要一个只能输入中文的textfiled

难点: 中文是由拼音拼出来的，拼音是英文字母

解决: 创建了一个Help 来负责处理和替换字符串

代码: 代码如下

.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
// 筛选管理类
@interface ChineseNotificationHelp : NSObject
+ (instancetype)ChineseNotificationHelpShareWithTextFiled:(UITextField *)textFiled;
@end

.m

#import "ChineseNotificationHelp.h"
@interface ChineseNotificationHelp ()
@property (nonatomic,strong)UITextField *textFiled;
@end
@implementation ChineseNotificationHelp
+ (instancetype)ChineseNotificationHelpShareWithTextFiled:(UITextField *)textFiled{
    static ChineseNotificationHelp *share = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        share = [[ChineseNotificationHelp alloc] init];
    });
    share.textFiled = textFiled;
    return share;
}
- (instancetype)init{
    self = [super init];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFiledEditChanged)
                                                   name:@"UITextFieldTextDidChangeNotification"
                                                 object:nil];
    }
    return self;
}
- (void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"UITextFieldTextDidChangeNotification" object:nil];
}
-(void)textFiledEditChanged{
    [self textFiledTextChange:self.textFiled];
}
- (void)textFiledTextChange:(UITextField *)textField{
    NSString *string = textField.text;
    NSArray *currentar = [UITextInputMode activeInputModes];// 键盘输入模式
    UITextInputMode *current = [currentar firstObject];
    NSString *lang = current.primaryLanguage;
    if(![lang isEqualToString:@"zh-Hans"]) return;
    UITextRange *selectedRange = [textField markedTextRange];
    //获取高亮部分
    UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
    if(position) return;// 有高亮则不处理
    // 过滤非汉字
    NSMutableString *chinese = string.mutableCopy;
    for (int i = 0; i<string.length; i++) {
        int a = [string characterAtIndex:i];
        if (a > 0x4e00 && a < 0x9fff) continue;
        [chinese replaceCharactersInRange:NSMakeRange(i,1) withString:@" "];
    }
    // 除去所有空格
    textField.text = [self removeSpaceAndNewline:chinese];
}
// 删除kon
- (NSString *)removeSpaceAndNewline:(NSString *)str
{
    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return temp;
}
@end

使用

// 只需要一句话就解决了  [ChineseNotificationHelp ChineseNotificationHelpShareWithTextFiled:chineseText];
    chineseText = [[UITextField alloc]initWithFrame:CGRectMake(10, 100, [UIScreen mainScreen].bounds.size.width-20, 50)];
    chineseText.backgroundColor = [UIColor lightGrayColor];
    chineseText.placeholder =@"只能输入汉字";
    [self.view addSubview:chineseText];
    [ChineseNotificationHelp ChineseNotificationHelpShareWithTextFiled:chineseText];

附加篇幅

问题：在上文的前提下英文九宫格输入法下，连点任意一个字符导致出现删除情况
解决：

if(self.beforeString && self.beforeString.length > textField.text.length && [chinese containsString:@" "]){
        //英文切换过程中处理出现删减的bug
        textField.text = self.beforeString;
        return;
    }

更正：(.m如下)

#import "ChineseNotificationHelp.h"
@interface ChineseNotificationHelp ()
@property (nonatomic,strong)UITextField *textFiled;
@property (nonatomic,strong)NSString *beforeString;
@end
@implementation ChineseNotificationHelp
+ (instancetype)ChineseNotificationHelpShareWithTextFiled:(UITextField *)textFiled{
    static ChineseNotificationHelp *share = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        share = [[ChineseNotificationHelp alloc] init];
    });
    share.textFiled = textFiled;
    return share;
}
- (instancetype)init{
    self = [super init];
    if (self) {
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textFiledEditChanged)
                                                   name:@"UITextFieldTextDidChangeNotification"
                                                 object:nil];
    }
    return self;
}
- (void)dealloc{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"UITextFieldTextDidChangeNotification" object:nil];
}
-(void)textFiledEditChanged{
    [self textFiledTextChange:self.textFiled];
}
- (void)textFiledTextChange:(UITextField *)textField{
    NSString *string = textField.text;
    NSLog(@"1.=%@",textField.text);
    NSArray *currentar = [UITextInputMode activeInputModes];// 键盘输入模式
    UITextInputMode *current = [currentar firstObject];
    NSString *lang = current.primaryLanguage;
    if(![lang isEqualToString:@"zh-Hans"]) return;
    UITextRange *selectedRange = [textField markedTextRange];
    //获取高亮部分
    UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
    if(position) return;// 有高亮则不处理
    // 过滤非汉字
    NSMutableString *chinese = string.mutableCopy;
    for (int i = 0; i<string.length; i++) {
        int a = [string characterAtIndex:i];
        if (a > 0x4e00 && a < 0x9fff) continue;
        [chinese replaceCharactersInRange:NSMakeRange(i,1) withString:@" "];
    }
    // 除去所有空格
    textField.text = [self removeSpaceAndNewline:chinese];
    NSLog(@"2.=%@",textField.text);
    if(self.beforeString && self.beforeString.length > textField.text.length && [chinese containsString:@" "]){
        //英文切换过程中处理出现删减的bug
        textField.text = self.beforeString;
        return;
    }
    self.beforeString = textField.text;
}
// 删除kon
- (NSString *)removeSpaceAndNewline:(NSString *)str
{
    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return temp;
}
@end