UITextField限制输入中文字数

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前面写一了篇，UITextField Category来限制输入的字数，是有个Bug的，要输入中文时会crash。如今改动了下。代码例如以下

.h文件

#import <UIKit/UIKit.h>@interface UITextField (LimitLength)
/**
* 使用时仅仅要调用此方法，加上一个长度(int)。就能够实现了字数限制,汉字不能够
*
* @param length
*/
- (void)limitTextLength:(int)length;
/**
* uitextField 抖动效果
*/
- (void)shake;
@end

.m文件

#import "UITextField+LimitLength.h"
#import <objc/runtime.h>@implementation UITextField (LimitLength)
static NSString *kLimitTextLengthKey = @"kLimitTextLengthKey";
- (void)limitTextLength:(int)length
{
objc_setAssociatedObject(self, (__bridge const void *)(kLimitTextLengthKey), [NSNumber numberWithInt:length], OBJC_ASSOCIATION_RETAIN_NONATOMIC); [self addTarget:self action:@selector(textFieldTextLengthLimit:) forControlEvents:UIControlEventEditingChanged];}
- (void)textFieldTextLengthLimit:(id)sender
{
NSNumber *lengthNumber = objc_getAssociatedObject(self, (__bridge const void *)(kLimitTextLengthKey));
int length = [lengthNumber intValue];
//以下是改动部分
bool isChinese;//推断当前输入法是否是中文
NSArray *currentar = [UITextInputMode activeInputModes];
UITextInputMode *current = [currentar firstObject];
//[[UITextInputMode currentInputMode] primaryLanguage]，废弃的方法
if ([current.primaryLanguage isEqualToString: @"en-US"]) {
isChinese = false;
}
else
{
isChinese = true;
} if(sender == self) {
// length是自己设置的位数
NSString *str = [[self text] stringByReplacingOccurrencesOfString:@"?" withString:@""];
if (isChinese) { //中文输入法下
UITextRange *selectedRange = [self markedTextRange];
//获取高亮部分
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];
// 没有高亮选择的字，则对已输入的文字进行字数统计和限制
if (!position) {
if ( str.length>=length) {
NSString *strNew = [NSString stringWithString:str];
[self setText:[strNew substringToIndex:length]];
}
}
else
{
// NSLog(@"输入的"); }
}else{
if ([str length]>=length) {
NSString *strNew = [NSString stringWithString:str];
[self setText:[strNew substringToIndex:length]];
}
}
}
}- (void)shake
{
CAKeyframeAnimation *keyAn = [CAKeyframeAnimation animationWithKeyPath:@"position"];
[keyAn setDuration:0.5f];
NSArray *array = [[NSArray alloc] initWithObjects:
[NSValue valueWithCGPoint:CGPointMake(self.center.x, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x-5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x+5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x-5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x+5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x-5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x+5, self.center.y)],
[NSValue valueWithCGPoint:CGPointMake(self.center.x, self.center.y)],
nil];
[keyAn setValues:array]; NSArray *times = [[NSArray alloc] initWithObjects:
[NSNumber numberWithFloat:0.1f],
[NSNumber numberWithFloat:0.2f],
[NSNumber numberWithFloat:0.3f],
[NSNumber numberWithFloat:0.4f],
[NSNumber numberWithFloat:0.5f],
[NSNumber numberWithFloat:0.6f],
[NSNumber numberWithFloat:0.7f],
[NSNumber numberWithFloat:0.8f],
[NSNumber numberWithFloat:0.9f],
[NSNumber numberWithFloat:1.0f],
nil];
[keyAn setKeyTimes:times]; [self.layer addAnimation:keyAn forKey:@"TextAnim"];
}
@end