Mac开发基础12-NSTextField（二）

NSTextField 是一个功能强大的控件，不仅可以作为简单的文本输入框，还可以实现更多高级功能。例如，支持富文本、实现自定义绘制、处理复杂的输入校验等。

进阶使用和技巧

1. 富文本显示与编辑

NSTextField 支持富文本，也就是说你可以为文本设置不同的颜色、字体、大小等。

设置富文本

Objective-C

NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:@"Hello, World!"
                                                                 attributes:@{
                                                                              NSForegroundColorAttributeName: [NSColor blueColor],
                                                                              NSFontAttributeName: [NSFont fontWithName:@"Helvetica-Bold" size:16]
                                                                              }];
[self.textField setAttributedStringValue:attrString];

Swift

let attrString = NSAttributedString(string: "Hello, World!", attributes: [
    .foregroundColor: NSColor.blue,
    .font: NSFont(name: "Helvetica-Bold", size: 16)!
])
textField.attributedStringValue = attrString

2. 自定义绘制文本字段

可以通过子类化 NSTextField 实现自定义的绘制逻辑，以实现独特的 UI 效果。

自定义绘制

Objective-C

@implementation CustomTextField

- (void)drawRect:(NSRect)dirtyRect {
    [super drawRect:dirtyRect];
    
    // 自定义绘制背景
    [[NSColor whiteColor] setFill];
    NSRectFill(dirtyRect);
    
    // 自定义绘制文本
    NSDictionary *attributes = @{
                                 NSFontAttributeName: [NSFont systemFontOfSize:14],
                                 NSForegroundColorAttributeName: [NSColor blackColor]
                                 };
    NSAttributedString *attrString = [[NSAttributedString alloc] initWithString:self.stringValue attributes:attributes];
    [attrString drawInRect:dirtyRect];
}

@end

Swift

class CustomTextField: NSTextField {
    
    override func draw(_ dirtyRect: NSRect) {
        super.draw(dirtyRect)
        
        // 自定义绘制背景
        NSColor.white.setFill()
        dirtyRect.fill()
        
        // 自定义绘制文本
        let attributes: [NSAttributedString.Key: Any] = [
            .font: NSFont.systemFont(ofSize: 14),
            .foregroundColor: NSColor.black
        ]
        let attrString = NSAttributedString(string: self.stringValue, attributes: attributes)
        attrString.draw(in: dirtyRect)
    }
}

3. 定制化输入校验与过滤

可以使用 NSTextFieldDelegate 来实现定制化的输入校验和过滤功能。

实现输入过滤

Objective-C

- (BOOL)control:(NSControl *)control textView:(NSTextView *)textView doCommandBySelector:(SEL)commandSelector {
    if (commandSelector == @selector(insertNewline:)) {
        NSString *inputText = [textView string];
        // 自定义校验逻辑
        if ([self isValidInput:inputText]) {
            return NO; // 允许插入新行
        } else {
            return YES; // 禁止插入新行
        }
    }
    return NO;
}

Swift

func control(_ control: NSControl, textView: NSTextView, doCommandBy commandSelector: Selector) -> Bool {
    if commandSelector == #selector(insertNewline(_:)) {
        let inputText = textView.string
        // 自定义校验逻辑
        if isValidInput(inputText) {
            return false // 允许插入新行
        } else {
            return true // 禁止插入新行
        }
    }
    return false
}

4. 处理剪切板操作

可以拦截并处理剪切板（拷贝、剪切、粘贴）操作，从而实现更多控制。

自定义剪切板操作处理

Objective-C

- (void)paste:(id)sender {
    NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
    NSString *pasteString = [pasteboard stringForType:NSPasteboardTypeString];
    
    // 自定义粘贴逻辑
    if ([self isValidInput:pasteString]) {
        [self setStringValue:pasteString];
    } else {
        NSBeep(); // 发出警告声
    }
}

Swift

override func paste(_ sender: Any?) {
    let pasteboard = NSPasteboard.general
    if let pasteString = pasteboard.string(forType: .string) {
        // 自定义粘贴逻辑
        if isValidInput(pasteString) {
            self.stringValue = pasteString
        } else {
            NSBeep() // 发出警告声
        }
    }
}

5. 自定义工具类封装

封装一个 NSTextField 的工具类，提供多个接口供外部使用，可灵活定制。

Objective-C

@interface NSTextFieldCustomizer : NSObject

@property (nonatomic, strong) NSTextField *textField;

- (instancetype)initWithTextField:(NSTextField *)textField;

- (void)setPlaceholder:(NSString *)placeholder;
- (void)setTextColor:(NSColor *)color;
- (void)setFont:(NSFont *)font;
- (void)setAlignment:(NSTextAlignment)alignment;
- (void)setEditable:(BOOL)editable;
- (void)setBordered:(BOOL)bordered;
- (void)setBackgroundColor:(NSColor *)color;

@end

@implementation NSTextFieldCustomizer

- (instancetype)initWithTextField:(NSTextField *)textField {
    self = [super init];
    if (self) {
        _textField = textField;
    }
    return self;
}

- (void)setPlaceholder:(NSString *)placeholder {
    [self.textField setPlaceholderString:placeholder];
}

- (void)setTextColor:(NSColor *)color {
    [self.textField setTextColor:color];
}

- (void)setFont:(NSFont *)font {
    [self.textField setFont:font];
}

- (void)setAlignment:(NSTextAlignment)alignment {
    [self.textField setAlignment:alignment];
}

- (void)setEditable:(BOOL)editable {
    [self.textField setEditable:editable];
}

- (void)setBordered:(BOOL)bordered {
    [self.textField setBordered:bordered];
}

- (void)setBackgroundColor:(NSColor *)color {
    [self.textField setBackgroundColor:color];
}

@end

Swift

class NSTextFieldCustomizer {

    private weak var textField: NSTextField?

    init(textField: NSTextField) {
        self.textField = textField
    }

    func setPlaceholder(_ placeholder: String) {
        textField?.placeholderString = placeholder
    }

    func setTextColor(_ color: NSColor) {
        textField?.textColor = color
    }

    func setFont(_ font: NSFont) {
        textField?.font = font
    }

    func setAlignment(_ alignment: NSTextAlignment) {
        textField?.alignment = alignment
    }

    func setEditable(_ editable: Bool) {
        textField?.isEditable = editable
    }

    func setBordered(_ bordered: Bool) {
        textField?.isBordered = bordered
    }

    func setBackgroundColor(_ color: NSColor) {
        textField?.backgroundColor = color
    }
}

使用示例

Objective-C

NSTextField *textField = [[NSTextField alloc] initWithFrame:NSMakeRect(0, 0, 200, 22)];
NSTextFieldCustomizer *customizer = [[NSTextFieldCustomizer alloc] initWithTextField:textField];
[customizer setPlaceholder:@"Enter your name"];
[customizer setTextColor:[NSColor blueColor]];
[customizer setFont:[NSFont fontWithName:@"Helvetica" size:14]];
[customizer setAlignment:NSTextAlignmentCenter];
[customizer setEditable:YES];
[customizer setBordered:YES];
[customizer setBackgroundColor:[NSColor whiteColor]];

Swift

let textField = NSTextField(frame: NSMakeRect(0, 0, 200, 22))
let customizer = NSTextFieldCustomizer(textField: textField)
customizer.setPlaceholder("Enter your name")
customizer.setTextColor(.blue)
customizer.setFont(NSFont(name: "Helvetica", size: 14)!)
customizer.setAlignment(.center)
customizer.setEditable(true)
customizer.setBordered(true)
customizer.setBackgroundColor(.white)