iOS UILabel高度

Question

我想在我的視圖的頂部添加一個UILabel，它可以是多行。我已經研究過，但是我無法實現，因爲它只會顯示一行，而且我希望它能夠像所需的那樣大。我與自動佈局和當前代碼我這樣做是這樣的：

UILabel *label = [[UILabel alloc] init]; 
label.translatesAutoresizingMaskIntoConstraints = NO; 
label.text = @"jklljk sdkhfdjkdsfjhkfk fhs fdh fk dksdks dfss s dfs dfs fsdkdfks dfks dfks df k dfh"; 
label.numberOfLines = 0; 

NSDictionary *views = @{@"label" : label}; 
[self.view addSubview:label]; 
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label]|" options:0 metrics:nil views:views]]; 
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[label(>=20)]" options:0 metrics:nil views:views]]; 

Answer 1

你需要設置一個幀標籤來設置它在視圖初始位置。

從視圖編程指南：

當添加一個子視圖到其父，子視圖的當前幀的矩形表示其父視圖內的初始位置。

Answer 2

嘗試調用：

[self.view layoutIfNeeded]; 

後添加的約束。這應該用新的限制來更新視圖。

Answer 3

如果您可以通過界面構建​​器添加標籤，它將節省大量的標籤屬性代碼，儘管從您所描述的內容來看，如果您使用下面的代碼（替換所需的位置，大小和文本值），那麼這個標籤會根據你填充的內容而改變。我一直使用它，完美地工作。

UILabel *label = [[UILabel alloc] initWithFrame:GCRectMake(0,0,300, 50)]; //these values to be changed to reflect where you want the label to appear, initial position and size, width etc. 
//setting up the label attributes etc 
label.numberOfLines = 0; //This means there's no limit to lines of text. 
label.font = [UIFont systemFontOfSize:13]; 
label.textColor = [UIColor blackColor]; 

NSString *content = YOUR_TEXT;// your example @"jklljk sdkhfdjkdsfjhkfk fhs fdh fk dksdks dfss s dfs dfs fsdkdfks dfks dfks df k dfh"; 

CGSize maximumLabelSize = CGSizeMake(300, 1000); //For example - the height can be changed to any maximum value. 

NSDictionary *stringAttributes = [NSDictionary dictionaryWithObject:[UIFont systemFontOfSize:13] forKey: NSFontAttributeName]; //This allows a calculation to be made of the space taken up, so if you're using a custom or large font it will calculate accordingly. 

CGSize newExpectedLabelSize = [content boundingRectWithSize:maximumLabelSize options:NSStringDrawingTruncatesLastVisibleLine|NSStringDrawingUsesLineFragmentOrigin attributes:stringAttributes context:nil].size; 

CGRect frame = label.frame; 
frame.size.height = newExpectedLabelSize.height; 
label.frame = frame; //This last line should change the height of your label according to what it needs to be to have all the text visible and over multiple lines. 

我希望這可以幫助你找到你要找的東西。

（這取代了需要任何約束的編碼，你有太多。）

乾杯，吉姆