我想创建一个弹出窗口，让用户知道他们是否尝试输入重复信息。所以最初我有一个会弹出并消失的UILabel。
UILabel *toastView = [[UILabel alloc] init];
toastView.alpha = 0;
toastView.layer.cornerRadius = 4.0f;
toastView.layer.borderColor = [UIColor colorWithRed:200.0/255.0 green:199.0/255.0 blue:204.0/255.0 alpha:1].CGColor;
CGFloat scale = [[UIScreen mainScreen] scale];
if (scale == 2.0) {
// retina screen;
toastView.layer.borderWidth = 0.5;
} else {
// non-retina screen
toastView.layer.borderWidth = 1.0;
}
toastView.backgroundColor = [UIColor colorWithRed:63.0/255.0 green:63.0/255.0 blue:63.0/255.0 alpha:1];
toastView.textAlignment = NSTextAlignmentCenter;
[toastView setAdjustsFontSizeToFitWidth:YES];
toastView.text = @" E-Mail has already been added ";
toastView.font = [UIFont fontWithName:@"HelveticaNeue" size:toastView.font.pointSize];
toastView.textColor = [UIColor whiteColor];
[toastView setTranslatesAutoresizingMaskIntoConstraints:NO];
[toastView.layer setMasksToBounds:YES];
[self.superview.superview.superview addSubview:toastView];
[[UIApplication sharedApplication].keyWindow bringSubviewToFront:toastView];
[toastView.bottomAnchor constraintEqualToAnchor:self.superview.superview.superview.centerYAnchor].active = YES;
[toastView.centerXAnchor constraintEqualToAnchor:self.superview.superview.superview.centerXAnchor].active = YES;
[toastView.heightAnchor constraintEqualToConstant:round(self.superview.superview.superview.frame.size.height/12)].active = YES;
[toastView.widthAnchor constraintEqualToConstant:round(self.superview.superview.superview.frame.size.width/1.5)].active = YES;
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0.95;
} completion:^(BOOL finished) {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0;
} completion:nil];
});
}];
这很好用。然后我想添加一个图像，所以我决定将这个弹出窗口的创建移动到一个方法，该方法接收视图和消息，并生成一个带有UILabel和UIImageView的弹出视图。这是代码：
+(void)toastAlert:(UIView*)view message:(NSString*)message {
UIView *toastView = [[UIView alloc] init];
UILabel *toastLabel = [[UILabel alloc] init];
UIImage *infoImage = [UIImage imageNamed:@"info_white"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:infoImage];
toastView.alpha = 0;
toastView.layer.cornerRadius = 4.0f;
toastView.layer.borderColor = [UIColor colorWithRed:200.0/255.0 green:199.0/255.0 blue:204.0/255.0 alpha:1].CGColor;
CGFloat scale = [[UIScreen mainScreen] scale];
if (scale == 2.0) {
// retina screen;
toastView.layer.borderWidth = 0.5;
} else {
// non-retina screen
toastView.layer.borderWidth = 1.0;
}
[toastLabel setTextAlignment:NSTextAlignmentCenter];
[toastLabel setAdjustsFontSizeToFitWidth:YES];
[toastLabel setText:[NSString stringWithFormat:@"%@", message]];
[toastLabel setFont:[UIFont fontWithName:@"HelveticaNeue" size:toastLabel.font.pointSize]];
[toastLabel setTextColor: [UIColor whiteColor]];
toastView.backgroundColor = [UIColor colorWithRed:63.0/255.0 green:63.0/255.0 blue:63.0/255.0 alpha:1];
[toastView setTranslatesAutoresizingMaskIntoConstraints:NO];
[toastView.layer setMasksToBounds:YES];
[view addSubview:toastView];
[[UIApplication sharedApplication].keyWindow bringSubviewToFront:toastView];
[toastView addSubview:toastLabel];
[toastView addSubview:imageView];
[toastView.bottomAnchor constraintEqualToAnchor:view.centerYAnchor].active = YES;
[toastView.centerXAnchor constraintEqualToAnchor:view.centerXAnchor].active = YES;
[toastView.heightAnchor constraintEqualToConstant:round(view.frame.size.height/12)].active = YES;
[toastView.widthAnchor constraintEqualToConstant:round(view.frame.size.width/1.5)].active = YES;
[imageView.centerYAnchor constraintEqualToAnchor:toastView.centerYAnchor].active = YES;
[imageView.leadingAnchor constraintEqualToAnchor:toastView.leadingAnchor constant:padding].active = YES;
[imageView.heightAnchor constraintEqualToConstant:toastView.frame.size.height/2].active = YES;
[imageView.widthAnchor constraintEqualToAnchor:toastView.heightAnchor].active = YES;
[toastLabel.centerYAnchor constraintEqualToAnchor:toastView.centerYAnchor].active = YES;
[toastLabel.centerXAnchor constraintEqualToAnchor:toastView.centerXAnchor constant:imageView.frame.size.width + padding*2].active = YES;
[toastLabel.leadingAnchor constraintEqualToAnchor:imageView.trailingAnchor constant:padding].active = YES;
[toastLabel.heightAnchor constraintEqualToConstant:toastView.frame.size.height/2].active = YES;
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0.95;
} completion:^(BOOL finished) {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0;
} completion:nil];
});
}];
}
然而，不管我做什么，我只能让UIView出现，没有文字或UILabel出现过。当我添加UIImageView时，它会显示但是会影响整个toastView的大小调整。
我还是一名初级开发人员，我确信我错过了一些基本的东西......任何人都可以向我解释我做错了什么吗？ （不只是寻找一个直接的答案，因为解释更有价值）
答案 0 :(得分：1)
所以我认为你的自动调整掩码与你的约束相冲突。那并从CGRectZero开始。我将尝试解决每个项目，以便您知道出了什么问题。这是工作代码。
-(void)alteredToastAlert:(UIView*)targetView message:(NSString*)message {
CGFloat padding = 10.0;
// i like to start with real frames buggy things happen with CGRectZero
UIView *toastView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 300, 200)];
//turn all resizing masks off
[toastView setTranslatesAutoresizingMaskIntoConstraints:NO];
UILabel *toastLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 300, 200)];
[toastLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
UIImage *infoImage = [UIImage imageNamed:@"info_white"];
UIImageView *imageView = [[UIImageView alloc] initWithImage:infoImage];
[imageView setTranslatesAutoresizingMaskIntoConstraints:NO];
//has a size but intrinsic
toastView.alpha = 0;
toastView.layer.cornerRadius = 4.0f;
toastView.layer.borderColor = [UIColor colorWithRed:200.0/255.0 green:199.0/255.0 blue:204.0/255.0 alpha:1].CGColor;
CGFloat scale = [[UIScreen mainScreen] scale];
if (scale == 2.0) {
// retina screen;
toastView.layer.borderWidth = 0.5;
} else {
// non-retina screen
toastView.layer.borderWidth = 1.0;
}
[toastLabel setTextAlignment:NSTextAlignmentCenter];
[toastLabel setText:[NSString stringWithFormat:@"%@", message]];
[toastLabel setFont:[UIFont fontWithName:@"HelveticaNeue" size:22]];
[toastLabel setTextColor: [UIColor whiteColor]];
[toastLabel setMinimumScaleFactor:0.01];
toastView.backgroundColor = [UIColor colorWithRed:63.0/255.0 green:63.0/255.0 blue:63.0/255.0 alpha:1];
[toastView setTranslatesAutoresizingMaskIntoConstraints:NO];
[toastView.layer setMasksToBounds:YES];
[targetView addSubview:toastView];
[[UIApplication sharedApplication].keyWindow bringSubviewToFront:toastView];
//adding here but everything has a frame so it is not size 0. Then apply autolayout
[toastView addSubview:toastLabel];
[toastView addSubview:imageView];
[toastView.bottomAnchor constraintEqualToAnchor:targetView.centerYAnchor].active = YES;
[toastView.centerXAnchor constraintEqualToAnchor:targetView.centerXAnchor].active = YES;
[toastView.heightAnchor constraintEqualToConstant:round(targetView.frame.size.height/12)].active = YES;
[toastView.widthAnchor constraintEqualToConstant:round(targetView.frame.size.width/1.5)].active = YES;
[imageView.centerYAnchor constraintEqualToAnchor:toastView.centerYAnchor].active = YES;
[imageView.leadingAnchor constraintEqualToAnchor:toastView.leadingAnchor constant:padding].active = YES;
[imageView.heightAnchor constraintEqualToConstant:toastView.frame.size.height/2].active = YES;
[imageView.widthAnchor constraintEqualToAnchor:toastView.heightAnchor].active = YES;
imageView.backgroundColor = [UIColor redColor];
[toastLabel.centerYAnchor constraintEqualToAnchor:toastView.centerYAnchor].active = YES;
[toastLabel.leadingAnchor constraintEqualToAnchor:imageView.trailingAnchor constant:padding].active = YES;
// have to have a trailing to keep it inside the view
[toastLabel.trailingAnchor constraintEqualToAnchor:toastView.trailingAnchor constant:padding].active = YES;
[toastLabel.heightAnchor constraintEqualToConstant:toastView.frame.size.height/2].active = YES;
toastView.alpha = 1;
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0.95;
} completion:^(BOOL finished) {
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
[UIView animateWithDuration:0.3 animations:^{
toastView.alpha = 0;
} completion:^(BOOL finished){
//may need to remove from superview
}];
});
}];
}
1）你会注意到我开始设置帧。我这样做是因为我注意到从CGRectZero开始做一些疯狂的事情。我们最终将通过自动布局来控制视图，但是开始我设置帧。 imageview将建立它的内在框架。
2）接下来我告诉系统不要从自动调整掩码创建约束。我为toastView执行此操作以及标签和imageview。
3）我告诉标签文本的最小比例因子，对于任意的字体大小，我的值为22。您可能会将其提高到50并且仍然会缩小。我想因为CGRectZero你的字体大小以前是0但我不确定
4）我让你的约束与标签上可能有尾随约束的版本一起工作，但我认为就是这样。你可以仔细看看。
5）当所有这一切都完成后，不要忘记从它的superview或你传递的视图中删除toastView，因为即使alpha为0，它仍然存在。