在UITextField中检测退格事件

我正在寻找有关如何捕获退格事件的解决方案,大多数堆栈溢出答案都在Objective-C中,但是我需要使用Swift语言。

首先,我为UITextField设置了委托,并将其设置为self

self.textField.delegate = self;

然后,我知道使用shouldChangeCharactersInRange委托方法来检测是否按下了退格键,因为所有代码都在Objective-

C中。我需要在Swift中使用以下方法。

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

const char * _char = [string cStringUsingEncoding:NSUTF8StringEncoding];

int isBackSpace = strcmp(_char, "\b");

if (isBackSpace == -8) {

// NSLog(@"Backspace was pressed");

}

return YES;

}

回答:

斯威夫特4.2

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

if let char = string.cString(using: String.Encoding.utf8) {

let isBackSpace = strcmp(char, "\\b")

if (isBackSpace == -92) {

print("Backspace was pressed")

}

}

return true

}

较早的Swift版本

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

let char = string.cStringUsingEncoding(NSUTF8StringEncoding)!

let isBackSpace = strcmp(char, "\\b")

if (isBackSpace == -92) {

println("Backspace was pressed")

}

return true

}

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