设置NSTextView的占位符字符串

Question

有什么办法可以像NSTextField那样设置NSTextView的占位符字符串吗？我已经检查过该物业但找不到它。我搜查了一些问题，但没有一个正确的解释。

Answer 1

我在网上找到了这个答案。 Philippe Mougin做了这个。

static NSAttributedString *placeHolderString; 

@implementation TextViewWithPlaceHolder 

+(void)initialize 
{ 
    static BOOL initialized = NO; 
    if (!initialized) 
{ 
    NSColor *txtColor = [NSColor grayColor]; 
    NSDictionary *txtDict = [NSDictionary dictionaryWithObjectsAndKeys:txtColor, NSForegroundColorAttributeName, nil]; 
    placeHolderString = [[NSAttributedString alloc] initWithString:@"This is my placeholder text" attributes:txtDict]; 
} 
} 

- (BOOL)becomeFirstResponder 
{ 
    [self setNeedsDisplay:YES]; 
    return [super becomeFirstResponder]; 
} 

- (void)drawRect:(NSRect)rect 
{ 
    [super drawRect:rect]; 
if ([[self string] isEqualToString:@""] && self != [[self window] firstResponder]) 
[placeHolderString drawAtPoint:NSMakePoint(0,0)]; 
} 

- (BOOL)resignFirstResponder 
{ 
    [self setNeedsDisplay:YES]; 
    return [super resignFirstResponder]; 
} 

@end 

Answer 2

雨燕2.0

var placeHolderTitleString: NSAttributedString = NSAttributedString(string: "Place Holder Value", attributes: [NSForegroundColorAttributeName : NSColor.grayColor()]) 

override func becomeFirstResponder() -> Bool { 
    self.needsDisplay = true 
    return super.becomeFirstResponder() 
} 

override func drawRect(rect: NSRect) { 
    super.drawRect(rect) 

    if (self.string! == "") { 
     placeHolderString.drawAtPoint(NSMakePoint(0, 0)) 
    } 
} 

Answer 3

斯威夫特4

事实证明，有似乎已经成为一个NSTextViewplaceholderAttributedString属性未公开曝光。因此，您可以简单地在自己的子类中实现它并获取默认的占位符行为（类似于NSTextField）。

class PlaceholderTextView: NSTextView { 
    @objc var placeholderAttributedString: NSAttributedString? 
} 

如果此属性将来可用，则只需使用NSTextView而不是此子类。