runloop实现的同步弹窗

今天介绍使用runloop实现，用return返回点击的结果的方式，首先看一下自定义弹窗的实现代码：

KSPopupView *popup = [[KSPopupView alloc] init];
NSInteger buttonIndex = [popup doModal];
NSLog(@"选择了%ld", (long)buttonIndex);
@implementation KSPopupView {
BOOL _bModel;
NSInteger _selectBtnIndex;
}

• (NSInteger)doModal {
  [self performSelector:@selector(showAlert)];

  _bModel = YES;
  while (_bModel) {
  [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
  }

  return _selectBtnIndex;
  }

• (void)showAlert {
  UIView *view = [[UIView alloc] initWithFrame:CGRectMake(20, 100, 200, 100)];
  [view setBackgroundColor:[UIColor redColor]];
  UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 50, 30)];
  [button setTitle:@"ok" forState:UIControlStateNormal];
  [button setBackgroundColor:[UIColor greenColor]];
  [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
  [view addSubview:button];
  [[UIApplication sharedApplication].keyWindow addSubview:view];
  }

• (void)buttonClick:(UIButton *)button {
  [button.superview removeFromSuperview];
  _selectBtnIndex = 1;
  _bModel = NO;
  }
  ok，没有问题，假如你想使用系统自带的UIAlertView的话，也是一样的，只是不要在程序刚启动的时候调用，不然会无法弹出（原因暂时还不知道）,下面是UIAlertView的例子：

• (NSInteger)doModal {
  [self showAlert];
  _bModel = YES;
  while (_bModel) {
  [[NSRunLoop mainRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
  }

  return _selectBtnIndex;
  }

• (void)showAlert {
  UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"" message:@"okookoko" delegate:self cancelButtonTitle:@"cancel" otherButtonTitles:@"ok", nil];
  [alertView show];
  }

• (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
  _selectBtnIndex = buttonIndex;
  _bModel = NO;
  }