2019独角兽企业重金招聘Python工程师标准>>> 
1设置textField文字字数和格式限制
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSInteger existedLength = textField.text.length;
NSInteger selectedLength = range.length;
NSInteger replaceLength = string.length;
if (existedLength - selectedLength + replaceLength < 7) {
if ([string length]>0)
{
unichar single=[string characterAtIndex:0];//当前输入的字符
if ((single >='0' && single<='9'))//数据格式正确
{
return YES;
}else{
return NO;
}
}else{
return YES;
}
}else{
return NO;
}
}
2设置提示文字的大小，颜色
[textField setValue:[UIFont boldSystemFontOfSize:36] forKeyPath:@"_placeholderLabel.font"];
[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];