如何通过Objective-C编程设置Mac自定义屏幕分辨率？

Great question! You absolutely can set custom scaled resolutions like 2560x1600 on macOS using Objective-C. Those modes you’re seeing in other apps are software-scaled resolutions (often linked to HiDPI functionality)—the system renders content at the higher virtual resolution, then scales it down to your display’s physical 1920x1080 size for crisper UI and text. Here’s how to implement this:

How It Works #

Your display’s physical resolution is fixed (1920x1080 in your case), but macOS allows you to create virtual resolutions that the system uses for rendering. These scaled modes don’t force the display to output a higher hardware resolution—instead, they leverage the GPU to upscale/downscale content smoothly.

Objective-C Implementation #

First, import the required frameworks:

#import <CoreGraphics/CoreGraphics.h>
#import <Foundation/Foundation.h>

Function to Set Custom Resolution #

This function creates a scaled display mode and applies it to your target display:

BOOL setCustomScaledResolution(CGDirectDisplayID displayID, CGSize virtualResolution) {
    // Grab the display's native hardware mode to match its pixel format
    CGDisplayModeRef nativeMode = CGDisplayCopyDisplayMode(displayID);
    if (!nativeMode) {
        NSLog(@"Failed to get native display mode");
        return NO;
    }
    
    // Create a custom scaled mode: virtual resolution + native physical pixels
    CGDisplayModeRef customMode = CGDisplayModeCreateWithPixelResolution(
        NULL,
        virtualResolution.width,
        virtualResolution.height,
        CGDisplayModeGetPixelWidth(nativeMode),
        CGDisplayModeGetPixelHeight(nativeMode)
    );
    
    CFRelease(nativeMode);
    if (!customMode) {
        NSLog(@"Failed to create custom display mode");
        return NO;
    }
    
    // Apply the custom mode (requires accessibility permissions on macOS 10.14+)
    CGError error = CGDisplaySetDisplayMode(displayID, customMode, NULL);
    CFRelease(customMode);
    
    return error == kCGErrorSuccess;
}

Usage Example #

To set 2560x1600 on your main display:

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        CGDirectDisplayID mainDisplay = CGMainDisplayID();
        BOOL success = setCustomScaledResolution(mainDisplay, CGSizeMake(2560, 1600));
        
        if (success) {
            NSLog(@"Custom 2560x1600 resolution applied successfully!");
        } else {
            NSLog(@"Failed to apply custom resolution. Check permissions and display compatibility.");
        }
    }
    return 0;
}

Critical Notes #

• Accessibility Permissions: On macOS 10.14 (Mojave) and later, your app needs 辅助功能（Accessibility） permissions to modify display settings. Add the NSAccessibilityUsageDescription key to your Info.plist with a clear reason (e.g., "To adjust display resolution for optimal viewing"), then have users enable your app in System Preferences > Security & Privacy > Privacy > Accessibility.
• Display Compatibility: Not all displays support every possible scaled resolution. Some may have hardware limits that prevent certain virtual resolutions from working. Test on your target display to confirm.
• Reverting to Default: To switch back to the original resolution, save the native mode before making changes and reapply it later:

  CGDisplayModeRef originalMode = CGDisplayCopyDisplayMode(mainDisplay);
  // ... apply custom mode ...
  CGDisplaySetDisplayMode(mainDisplay, originalMode, NULL);
  CFRelease(originalMode);
  

Bonus: Hardware-Level Custom Resolutions (Rare) #

If your display actually supports higher hardware resolutions (e.g., via a newer HDMI/DP cable), you may need to add a custom hardware mode using lower-level APIs like IOService or CoreVideo. However, this is far less common—software scaling will cover most use cases like the 2560x1600 mode you mentioned.

内容的提问来源于stack exchange，提问作者Mark