整数字面值可以写为：
一个十进制数，没有前缀
一个二进制数，前缀是 0b
一个八进制数，前缀是 0o
一个十六进制数，前缀是 0x
设置textfield的placeholderLabel的颜色
[self.textField setValue:LineColor forKeyPath:@"placeholderLabel.textColor"];
self.textField.placeholder = @"这的字不影响placeholder,但是不能为空";
获取当前的控制器
- (UIViewController *)getCurrentVC{
UIWindow * window = [[UIApplication sharedApplication] keyWindow];
if (window.windowLevel != UIWindowLevelNormal){
NSArray *windows = [[UIApplication sharedApplication] windows];
for(UIWindow * tmpWin in windows){
if (tmpWin.windowLevel == UIWindowLevelNormal){
window = tmpWin;
break;
}
}
}
id nextResponder = nil;
UIViewController *appRootVC = window.rootViewController;
if (appRootVC.presentedViewController) {
nextResponder = appRootVC.presentedViewController;
}else{
UIView *frontView = [[window subviews] objectAtIndex:0];
nextResponder = [frontView nextResponder];
// nextResponder = appRootVC;//与上面有何区别
}
if ([nextResponder isKindOfClass:[UITabBarController class]]){
UITabBarController * tabbar = (UITabBarController *)nextResponder;
UINavigationController * nav = (UINavigationController *)tabbar.viewControllers[tabbar.selectedIndex];
// UINavigationController * nav = tabbar.selectedViewController;
return nav.childViewControllers.lastObject;
}else if ([nextResponder isKindOfClass:[UINavigationController class]]){
UIViewController * nav = (UIViewController *)nextResponder;
return nav.childViewControllers.lastObject;
}else{
return nextResponder;
}
}
