UITextField 光標的位置設置獲取

轉正：http://blog.csdn.net/reylen/article/details/17750523

UITextField 光標的位置設置獲取

通過給UITextField 加一個拓展

//#import "UITextField+ExtentRange.h"

#import <UIKit/UIKit.h>

@interface UITextField (ExtentRange)

- (NSRange) selectedRange;
- (void) setSelectedRange:(NSRange) range;

@end

// #import "UITextField+ExtentRange.m"

#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  // 備註：UITextField必須爲第一響應者纔有效
{
    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