objective-c - 像 Cocoa 中的 iTunes 一样滚动文本

Question

我已阅读答案:iTunes Song Title Scrolling in Cocoa

这是我编写的代码:

// ScrollingTextView.h
#import <Cocoa/Cocoa.h>

@interface ScrollingTextView : NSView {
    NSTimer *scroller;
    NSPoint point;
    NSString *text;
    NSTimeInterval speed;
    CGFloat stringWidth;
}

@property (nonatomic, copy) NSString *text;
@property (nonatomic) NSTimeInterval speed;

@end

// ScrollingTextView.m
#import "ScrollingTextView.h"

@implementation ScrollingTextView

@synthesize text;
@synthesize speed;

- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code here.
    }
    return self;
}

- (void)dealloc {
    [scroller invalidate];
}

- (void)setText:(NSString *)newText {
    text = [newText copy];
    NSLog(@"t: %@", text);
    point = NSZeroPoint;

    stringWidth = [newText sizeWithAttributes:nil].width;

    if (scroller == nil && speed > 0 && text != nil) {
        scroller = [NSTimer scheduledTimerWithTimeInterval:speed target:self selector:@selector(moveText:) userInfo:nil repeats:YES];
    }
}

- (void)setSpeed:(NSTimeInterval)newSpeed {
    if (newSpeed != speed) {
        speed = newSpeed;
        NSLog(@"s: %f", speed);
        [scroller invalidate];
        if (speed > 0 && text != nil) {
            scroller = [NSTimer scheduledTimerWithTimeInterval:speed target:self selector:@selector(moveText:) userInfo:nil repeats:YES];
        }
    }
}

- (void)moveText:(NSTimer *)timer {
    point.x = point.x - 1.0f;
    [self setNeedsDisplay:YES];
}

- (void)drawRect:(NSRect)dirtyRect {
    // Drawing code here.
    [super drawRect:dirtyRect];
    if (point.x + stringWidth < 0) {
        point.x += dirtyRect.size.width;
    }

    [text drawAtPoint:point withAttributes:nil];

    if (point.x < 0) {
        NSPoint otherPoint = point;
        otherPoint.x += dirtyRect.size.width;
        [text drawAtPoint:otherPoint withAttributes:nil];
    }
}

@end

然后，我将 NSView 拖到 Interface Builder 中的主窗口上，并将其类更改为“ScrollingTextView”。在 Controller 中我做:

ScrollingTextView *test = [[ScrollingTextView alloc] init];
[test setText:@"Test long text scrolling!"];
[test setSpeed:0.01];

但是当我运行它时没有任何反应，你能帮我一下吗？谢谢!

Answer 1

ScrollingTextView *test = [[ScrollingTextView alloc] init];

这样做意味着您正在创建一个新的 ScrollingTextView，而不是引用在 .xib 中创建和初始化的一个 Interface Builder

在您的 View Controller 中将ScrollingTextView设置为IBOutlet。

(IBOutlet)ScrollingTextView *test;

从界面构建器中分配拖入其中的 CustomView，作为 View Controller 的引用导出。这就是初始化 ScrollingTextView 类的方式。

现在调用你的 setTest: 和 setSpeed: 它应该可以正常工作。