项目中对昵称，用户名会限制一些输入个数 于是写了一个UITextField分类
@interface UITextField (LimitLength_h)
/**
* 使用时只要调用此方法，加上一个长度(int)，就可以实现了字数限制,汉字不可以
*
* @param length
*/
- (void)limitTextLength:(int)length;
@end
#import "UITextField+LimitLength_h.h"
#import <objc/runtime.h>
@implementation UITextField (LimitLength_h)
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];
//下面是修改部分
bool isChinese;//判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]];
}
}
}
}
@end
