iOS下的类似Android的toast提示

一般人会说，就是用那个MBProgressHUD不就行了吗？

的确是，MBProgressHUD能为我们做了好多loading指示器，但是toast不一样，它是在屏幕某个地方出现一行小提示，例如网络状态，出现的时候不会妨碍用户其他点击操作，只是MBProgressHUD它本身设计出发点并不如此，所以我介绍一个比较独特的开源文件。

先看头文件

#import <Foundation/Foundation.h>

#define kSGInfoAlert_fontSize       14
#define kSGInfoAlert_width          200
#define kMax_ConstrainedSize        CGSizeMake(250, 150)
#define kViewTag                    990

@interface SGInfoAlert : UIView{
    CGColorRef bgcolor_;
    NSString *info_;
    CGSize fontSize_;
}

// info为提示信息，frame为提示框大小，view是为消息框的superView（推荐Tabbarcontroller.view)
// vertical 为垂直方向上出现的位置 从 取值 0 ~ 1。
+ (SGInfoAlert *)showInfo:(NSString*)info
         bgColor:(CGColorRef)color
          inView:(UIView*)view 
        vertical:(float)height;

@end

再看.m文件

#import "SGInfoAlert.h"

@implementation SGInfoAlert


// 画出圆角矩形背景
static void addRoundedRectToPath(CGContextRef context, CGRect rect,
                                 float ovalWidth,float ovalHeight)
{
    float fw, fh;
    if (ovalWidth == 0 || ovalHeight == 0) { 
        CGContextAddRect(context, rect);
        return;
    }
    CGContextSaveGState(context); 
    CGContextTranslateCTM (context, CGRectGetMinX(rect), 
                           CGRectGetMinY(rect));
    CGContextScaleCTM (context, ovalWidth, ovalHeight); 
    fw = CGRectGetWidth (rect) / ovalWidth; 
    fh = CGRectGetHeight (rect) / ovalHeight; 
    CGContextMoveToPoint(context, fw, fh/2); 
    CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1); 
    CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1); 
    CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1); 
    CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1); 
    CGContextClosePath(context); 
    CGContextRestoreGState(context); 
}

- (id)initWithFrame:(CGRect)frame bgColor:(CGColorRef)color info:(NSString*)info{
    CGRect viewR = CGRectMake(0, 0, frame.size.width*1.2, frame.size.height*1.2);
    self = [super initWithFrame:viewR];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
        bgcolor_ = color;
        info_ = [[NSString alloc] initWithString:info];
        fontSize_ = frame.size;
    }
    return self;
}

- (void)drawRect:(CGRect)rect{
    CGContextRef context = UIGraphicsGetCurrentContext();
    // 背景0.8透明度
    CGContextSetAlpha(context, .8);
    addRoundedRectToPath(context, rect, 4.0f, 4.0f);
    CGContextSetFillColorWithColor(context, bgcolor_);
    CGContextFillPath(context);
    
    // 文字1.0透明度
    CGContextSetAlpha(context, 1.0);
//    CGContextSetShadowWithColor(context, CGSizeMake(0, -1), 1, [[UIColor whiteColor] CGColor]);
    CGContextSetFillColorWithColor(context, [UIColor flatPurpleColor].CGColor);
    float x = (rect.size.width - fontSize_.width) / 2.0;
    float y = (rect.size.height - fontSize_.height) / 2.0;
    CGRect r = CGRectMake(x, y, fontSize_.width, fontSize_.height);
    [info_ drawInRect:r withFont:[UIFont systemFontOfSize:kSGInfoAlert_fontSize] lineBreakMode:UILineBreakModeTailTruncation];
}

//- (void)dealloc{
//    [info_ release];
//    [super dealloc];
//}

// 从上层视图移除并释放
- (void)remove{
    [self removeFromSuperview];
}

// 渐变消失
- (void)fadeAway{
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:1.5f];
    self.alpha = .0;
    [UIView commitAnimations];
    [self performSelector:@selector(remove) withObject:nil afterDelay:1.5f];
}

+ (SGInfoAlert *)showInfo:(NSString *)info
         bgColor:(CGColorRef)color
          inView:(UIView *)view 
        vertical:(float)height{
    if ([view viewWithTag:kViewTag] != nil) {
        SGInfoAlert *alert = (SGInfoAlert *)[view viewWithTag:kViewTag];
        [alert remove];
    }
    height = height < 0 ? 0 : height > 1 ? 1 : height;
    CGSize size = [info sizeWithFont:[UIFont systemFontOfSize:kSGInfoAlert_fontSize]
                   constrainedToSize:kMax_ConstrainedSize];
    CGRect frame = CGRectMake(0, 0, size.width, size.height);
    SGInfoAlert *alert = [[SGInfoAlert alloc] initWithFrame:frame bgColor:color info:info];
    alert.center = CGPointMake(view.center.x, view.frame.size.height*height);
    alert.alpha = 0;
    [view addSubview:alert];
    alert.tag = kViewTag;
//    [alert release];
    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:.3f];
    alert.alpha = 1.0;
    [UIView commitAnimations];
//    [alert performSelector:@selector(fadeAway) withObject:nil afterDelay:3.5];
    return alert;
}

我注销了一些地方，使得它可以在ARC环境下使用