iOS开发一个简单的提示框

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

static char tipsKey;
static char tapKey;

@interface UIWindow (Extension)

+ (void)showTips:(NSString *)text;

@end

NS_ASSUME_NONNULL_END

#import "UIWindow+Extension.h"
#import "objc/runtime.h"

@implementation UIWindow (Extension)

+ (void)showTips:(NSString *)text {
    UITextView *tips = objc_getAssociatedObject(self, &tipsKey);
    if(tips) {
        [self dismiss];
        [NSThread sleepForTimeInterval:0.5f];
    }
    
    UIWindow *window = [[[UIApplication sharedApplication] delegate] window];
    CGFloat maxWidth = 200;
    CGFloat maxHeight = window.frame.size.height - 200;
    CGFloat commonInset = 10;
    UIFont  *font = [UIFont systemFontOfSize:12];
    NSMutableAttributedString *string = [[NSMutableAttributedString alloc] initWithString:text];
    [string addAttribute:NSFontAttributeName value:font range:NSMakeRange(0, string.length)];
    CGRect rect = [string boundingRectWithSize:CGSizeMake(maxWidth, 10000) options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading context:nil];
    CGSize size = CGSizeMake(ceilf(rect.size.width), ceilf(rect.size.height < maxHeight ? rect.size.height : maxHeight));
    CGRect textFrame = CGRectMake(window.frame.size.width/2 - (size.width + commonInset * 2)/2 , window.frame.size.height - (size.height + commonInset * 2) - 100, size.width  + commonInset * 2, size.height + commonInset * 2);
    tips = [[UITextView alloc] initWithFrame:textFrame];
    tips.text = text;
    tips.font = font;
    tips.textColor = [UIColor whiteColor];
    tips.backgroundColor = [UIColor blackColor];
    tips.layer.cornerRadius = 5;
    tips.editable = NO;
    tips.selectable = NO;
    tips.scrollEnabled = NO;
    tips.textContainer.lineFragmentPadding = 0;
    tips.contentInset = UIEdgeInsetsMake(commonInset, commonInset, commonInset, commonInset);
    
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handlerGuesture:)];
    [window addGestureRecognizer:tap];
    [window addSubview:tips];
    
    objc_setAssociatedObject(self, &tapKey, tap, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    objc_setAssociatedObject(self, &tipsKey, tips, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    
    [self performSelector:@selector(dismiss) withObject:nil afterDelay:2.0f];
}

+ (void)handlerGuesture:(UIGestureRecognizer *)sender {
    if(!sender || !sender.view) return;
    
    [self dismiss];
    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(dismiss) object: nil];
}

+ (void)dismiss {
    UIWindow *window = [[[UIApplication sharedApplication] delegate] window];
    UITapGestureRecognizer *tap = objc_getAssociatedObject(self, &tapKey);
    [window removeGestureRecognizer:tap];
    
    UITextView *tips = objc_getAssociatedObject(self, &tipsKey);
    [UIView animateWithDuration:0.5f delay:0.0f options:UIViewAnimationOptionCurveLinear animations:^{
        tips.alpha = 0.0f;
    } completion:^(BOOL finished) {
        [tips removeFromSuperview];
    }];
}

@end

#import "ViewController.h"
#import "UIWindow+Extension.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
   
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [UIWindow showTips:@"hello world !!!"];
}

@end