UITextField获取光标的位置以及改变光标的位置

创建一个类别

• xxxxx.h

//
//  UITextField+ExtentRange.h
//  HuiTing
//
//  Created by Jason on 2017/8/3.
//  Copyright © 2017年 Jason. All rights reserved.
//

#import <UIKit/UIKit.h>

@interface UITextField (ExtentRange)
- (NSRange) selectedRange;
- (void) setSelectedRange:(NSRange) range;
@end

• xxxxx.m

//
//  UITextField+ExtentRange.m
//  HuiTing
//
//  Created by Jason on 2017/8/3.
//  Copyright © 2017年 Jason. All rights reserved.
//

#import "UITextField+ExtentRange.h"

@implementation UITextField (ExtentRange)

- (NSRange) selectedRange
{
    UITextPosition* beginning = self.beginningOfDocument;
    
    UITextRange* selectedRange = self.selectedTextRange;
    UITextPosition* selectionStart = selectedRange.start;
    UITextPosition* selectionEnd = selectedRange.end;
    
    const NSInteger location = [self offsetFromPosition:beginning toPosition:selectionStart];
    const NSInteger length = [self offsetFromPosition:selectionStart toPosition:selectionEnd];
    
    return NSMakeRange(location, length);
}


- (void) setSelectedRange:(NSRange) range
{
    UITextPosition* beginning = self.beginningOfDocument;
    
    UITextPosition* startPosition = [self positionFromPosition:beginning offset:range.location];
    UITextPosition* endPosition = [self positionFromPosition:beginning offset:range.location + range.length];
    UITextRange* selectionRange = [self textRangeFromPosition:startPosition toPosition:endPosition];
    
    [self setSelectedTextRange:selectionRange];
}
@end