分别textFiled和 textView的代理方法中实现，如下：
1. textFiled中限制输入字符长度为6
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool{
if (range.location >= 6)
{
return false//限制长度
}
return true
}
2. textView中限制输入字符长度为5
func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
if range.location >= 5{
return false
}
return true
}
textView中还可以在这个方法中实现：
func textViewDidChange(textView: UITextView) {
if (100 - NSString(string: textView.text).length) < 0 {
var str = textView.text
let index1 = advance(str.endIndex, 100 - NSString(string: textView.text).length)
self.textView.text = str.substringToIndex(index1)
}
}
其他方法
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool{
var lengthOfString :NSInteger = count(string)
var fieldTextString : String = textField.text
var proposedNewLength : Int = count (fieldTextString) - range.length + lengthOfString;
var maxNum = 15
if (proposedNewLength > maxNum)
{
return false//限制长度
}
return true
}