JSJP_Student/jiaPei/Category/UITextField/UITextField+RQExtension.m

//
//  UITextField+RQExtension.m
//  RQCommon
//
//  Created by 张嵘 on 2018/11/23.
//  Copyright © 2018 张嵘. All rights reserved.
//

#import "UITextField+RQExtension.h"

@implementation UITextField (RQExtension)

- (void)rq_limitMaxLength:(NSInteger)maxLength {
	/// 修改昵称
	@weakify(self);
	[[[RACSignal merge:@[RACObserve(self, text),self.rac_textSignal]] skip:0] subscribeNext:^(NSString * text) {
		@strongify(self);
		UITextRange *selectedRange = [self markedTextRange];
		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,防止中文被截断
		if (position) return ;
		if (text.length <= maxLength) return;
		
		//中文和emoj表情存在问题，需要对此进行处理
		NSRange range;
		NSUInteger inputLength = 0;
		for(int i =0 ; i < text.length && inputLength <= maxLength; i += range.length){
			range = [self.text rangeOfComposedCharacterSequenceAtIndex:i];
			inputLength += [text substringWithRange:range].length;
			if (inputLength > maxLength) self.text = [text substringWithRange:NSMakeRange(0, range.location)];
		}
	}];
}
@end