iOS 限制TextField输入长度

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#import "MyInfoEditTableViewCell.h"
@interface MyInfoEditTableViewCell()<UITextFieldDelegate>
@property (weak, nonatomic) IBOutlet UITextField *editField;

@end

@implementation MyInfoEditTableViewCell
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    
    if (textField == self.editField) {
        //这里的if时候为了获取删除操作,如果没有次if会造成当达到字数限制后删除键也不能使用的后果.
        if (range.length == 1 && string.length == 0) {
            return YES;
        }
        else if (self.editField.text.length >= 30) {
            self.editField.text = [textField.text substringToIndex:30];
            return NO;
        }
    }
    return YES;
}

- (void)awakeFromNib {
    [super awakeFromNib];
    self.editField.delegate = self;
}

@end