如何在 iOS 中更改 UIAlertView 对话框的颜色？

Posted 2023-02-21

【中文标题】如何在 iOS 中更改 UIAlertView 对话框的颜色？

【英文标题】：How to change color of the UIAlertView dialog in iOS?

【发布时间】：2012-04-13 23:19:07

【问题描述】：

我有一个使用 UIAlertView 显示警报消息的应用程序。默认情况下，对话框的颜色为蓝色。谁能告诉我，如何改变它的颜色？可以改吗？

【问题讨论】：

浏览这个[以前讨论过的问题][1] [1]：***.com/questions/883208/…

【参考方案1】：

这样使用

   [CustomAlert setBackgroundColor:[UIColor blueColor] 
    withStrokeColor:[UIColor greenColor]];

.h 和 .m 文件的内容

CustomAlert.h

#import <UIKit/UIKit.h>

@interface CustomAlert : UIAlertView




+ (void) setBackgroundColor:(UIColor *) background 
    withStrokeColor:(UIColor *) stroke;

@end

CustomAlert.m

#import "CustomAlert.h"

@interface CustomAlert (Private)

- (void) drawRoundedRect:(CGRect) rect inContext:(CGContextRef) 
    context withRadius:(CGFloat) radius;

@end



static UIColor *fillColor = nil;
static UIColor *borderColor = nil;

@implementation CustomAlert

+ (void) setBackgroundColor:(UIColor *) background 
    withStrokeColor:(UIColor *) stroke

    if(fillColor != nil)
    
        [fillColor release];
        [borderColor release];
    

    fillColor = [background retain];
    borderColor = [stroke retain];


- (id)initWithFrame:(CGRect)frame

    if((self = [super initWithFrame:frame]))
    
        if(fillColor == nil)
        
            fillColor = [[UIColor blackColor] retain];
            borderColor = [[UIColor colorWithHue:0.625 
                saturation:0.0 brightness:0.8 alpha:0.8] 
                    retain];
        
    

    return self;


- (void)layoutSubviews

    for (UIView *sub in [self subviews])
    
        if([sub class] == [UIImageView class] && sub.tag == 0)
        
            // The alert background UIImageView tag is 0, 
            // if you are adding your own UIImageView's 
            // make sure your tags != 0 or this fix 
            // will remove your UIImageView's as well!
            [sub removeFromSuperview];
            break;
        
    


- (void)drawRect:(CGRect)rect
   
    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextClearRect(context, rect);
    CGContextSetAllowsAntialiasing(context, true);
    CGContextSetLineWidth(context, 0.0);
    CGContextSetAlpha(context, 0.8); 
    CGContextSetLineWidth(context, 2.0);
    CGContextSetStrokeColorWithColor(context, [borderColor CGColor]);
    CGContextSetFillColorWithColor(context, [fillColor CGColor]);

    // Draw background
    CGFloat backOffset = 2;
    CGRect backRect = CGRectMake(rect.origin.x + backOffset, 
        rect.origin.y + backOffset, 
        rect.size.width - backOffset*2, 
        rect.size.height - backOffset*2);

    [self drawRoundedRect:backRect inContext:context withRadius:8];
    CGContextDrawPath(context, kCGPathFillStroke);

    // Clip Context
    CGRect clipRect = CGRectMake(backRect.origin.x + backOffset-1, 
        backRect.origin.y + backOffset-1, 
        backRect.size.width - (backOffset-1)*2, 
        backRect.size.height - (backOffset-1)*2);

    [self drawRoundedRect:clipRect inContext:context withRadius:8];
    CGContextClip (context);

    //Draw highlight
    CGGradientRef glossGradient;
    CGColorSpaceRef rgbColorspace;
    size_t num_locations = 2;
    CGFloat locations[2] =  0.0, 1.0 ;
    CGFloat components[8] =  1.0, 1.0, 1.0, 0.35, 1.0, 1.0, 1.0, 0.06 ;
    rgbColorspace = CGColorSpaceCreateDeviceRGB();
    glossGradient = CGGradientCreateWithColorComponents(rgbColorspace, 
        components, locations, num_locations);

    CGRect ovalRect = CGRectMake(-130, -115, (rect.size.width*2), 
        rect.size.width/2);

    CGPoint start = CGPointMake(rect.origin.x, rect.origin.y);
    CGPoint end = CGPointMake(rect.origin.x, rect.size.height/5);

    CGContextSetAlpha(context, 1.0); 
    CGContextAddEllipseInRect(context, ovalRect);
    CGContextClip (context);

    CGContextDrawLinearGradient(context, glossGradient, start, end, 0);

    CGGradientRelease(glossGradient);
    CGColorSpaceRelease(rgbColorspace); 


- (void) drawRoundedRect:(CGRect) rrect inContext:(CGContextRef) context 
        withRadius:(CGFloat) radius

    CGContextBeginPath (context);

    CGFloat minx = CGRectGetMinX(rrect), midx = CGRectGetMidX(rrect), 
        maxx = CGRectGetMaxX(rrect);

    CGFloat miny = CGRectGetMinY(rrect), midy = CGRectGetMidY(rrect), 
        maxy = CGRectGetMaxY(rrect);

    CGContextMoveToPoint(context, minx, midy);
    CGContextAddArcToPoint(context, minx, miny, midx, miny, radius);
    CGContextAddArcToPoint(context, maxx, miny, maxx, midy, radius);
    CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, radius);
    CGContextAddArcToPoint(context, minx, maxy, minx, midy, radius);
    CGContextClosePath(context);


- (void)dealloc

    [super dealloc];


@end

【讨论】：

来自 Apple，The UIAlertView class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified.，您确定您的子类在所有情况下都能正常工作吗？你有没有在 App Store 上找到一个使用这个类的应用程序？

请使用 UIAlertView 的其他替代品，即使 UIAlertview 早就被弃用了。

【参考方案2】：

来自UIAlertView Class Reference：

UIAlertView 类旨在按原样使用，不支持子类化。此类的视图层次结构是私有的，不得修改。

【参考方案3】：

你必须实现你的UIAlertView。您无法更改默认的蓝色。

【参考方案4】：

使用 uiview 来显示警报而不是使用 UIAlertView 然后相应地更改该视图的颜色