您可以通过管理按钮的事件,如touchdown、touchupinside和touchoutside来实现这一点。
当按钮按下时,以0.2秒的延迟启动计时器,并从textDocumentProxy中删除最后一个字符,直到按钮的touchup方法触发,然后只需要使计时器失效即可。
[self.btnDelete addTarget:self action:@selector(btnTocuhDown:) forControlEvents:UIControlEventTouchDown];
[self.btnDelete addTarget:self action:@selector(btnTouchUp:) forControlEvents:UIControlEventTouchUpInside];
[self.btnDelete addTarget:self action:@selector(btnTouchUp:) forControlEvents:UIControlEventTouchUpOutside];
-(void) btnTocuhDown
NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(kpTimerMethod:) userInfo:nil repeats:YES];
self.kpTimer = timer;
__weak typeof(self)weakSelf = self;
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^(void){
if (timer == self.kpTimer) {
[weakSelf.kpTimer fire];
}
});
-(void)kpTimerMethod:(NSTimer *)timer
if (self.btnDelete.highlighted)
{
[self deleteLastCharacter];
}
else
{
[timer invalidate];
self.kpTimer = nil;
}
-(void)deleteLastCharacter
NSString *strInput = self.textDocumentProxy.documentContextBeforeInput;
if (strInput.length > 1)
NSString *coupleOfLastCharacters = [strInput substringWithRange:NSMakeRange(strInput.length-2, 2)];
if( [@"yo" caseInsensitiveCompare:coupleOfLastCharacters] == NSOrderedSame ) {
[self.textDocumentProxy deleteLastCharacter];
}
}
[self.textDocumentProxy deleteLastCharacter];
-(void) btnTouchUp
[self.kpTimer invalidate];
self.kpTimer = nil;