uitextfield限制输入长度（jtextfield只能输入数字）

前言

本文主要介绍使用UITextField限制只可输入中,英文,数字，我们可以使用NSPredicate正则表达式可以过滤，下面看看详细的步骤方法

首先设置UItextField的代理

实现如下方法:

1 2 3 4 5 6 7 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{ if ([self isInputRuleAndNumber:string] || [string isEqualToString:@""]) { return YES; } return NO; }

然后添加事件,因为选择输入法联想的词.是不会经过textField:shouldChangeCharactersInRange:replacementString:方法的

1	`[textField addTarget:self action:@selector(textFieldChanged:) forControlEvents:UIControlEventEditingChanged];`

实现:

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 - (void)textFieldChanged:(UITextField *)textField { NSString *toBeString = textField.text; NSString *lastString; if(toBeString.length>0) lastString=[toBeString substringFromIndex:toBeString.length-1]; if (![self isInputRuleAndNumber:toBeString]&&[self hasEmoji:lastString]) { textField.text = [self disable_emoji:toBeString]; return; } NSString *lang = [[textField textInputMode] primaryLanguage]; if([lang isEqualToString:@"zh-Hans"]) { UITextRange *selectedRange = [textField markedTextRange]; UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0]; if(!position) { NSString *getStr = [self getSubString:toBeString]; if(getStr && getStr.length > 0) { textField.text = getStr; } } } else{ NSString *getStr = [self getSubString:toBeString]; if(getStr && getStr.length > 0) { textField.text= getStr; } } }

再来实现限制:

pattern中,输入需要验证的通过的字符

小写a-z

大写A-Z

汉字\u4E00-\u9FA5

数字\u0030-\u0039

1 2 3 4 5 6 - (BOOL)isInputRuleAndNumber:(NSString *)str { NSString *pattern = @"[a-zA-Z\u4E00-\u9FA5\\u0030-\\u0039]"; NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern]; BOOL isMatch = [pred evaluateWithObject:str]; return isMatch; }

实现判断是否是Emoji

1 2 3 4 5 6 - (BOOL)hasEmoji:(NSString*)str{ NSString *pattern = @"[^\\u0020-\\u007E\\u00A0-\\u00BE\\u2E80-\\uA4CF\\uF900-\\uFAFF\\uFE30-\\uFE4F\\uFF00-\\uFFEF\\u0080-\\u009F\\u2000-\\u201f\r\n]"; NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", pattern]; BOOL isMatch = [pred evaluateWithObject:str]; return isMatch; }

字符限制

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 #define kMaxLength 20; -(NSString *)getSubString:(NSString*)string { NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000); NSData* data = [string dataUsingEncoding:encoding]; NSInteger length = [data length]; if (length > kMaxLength) { NSData *data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength)]; NSString *content = [[NSString alloc] initWithData:data1 encoding:encoding]; if (!content || content.length == 0) { data1 = [data subdataWithRange:NSMakeRange(0, kMaxLength - 1)]; content = [[NSString alloc] initWithData:data1 encoding:encoding]; } return content; } return nil; }