IOS 自定义控件之UIAlertview

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blog.csdn.net/hello_hwc

本文的内容

• demo展示以及说明
• 如何自定义一个alertview

希望通过本文，读者能够学到

• 自定义控件的UI布局
• 自定义控件如何用代理传递事件
• UIDynamic Animation

  以及UIKit角度的Animation的使用

• 熟悉面相接口编程的思想。

我的习惯是每讲解一些原理，都会写个demo。这个也不例外。

demo的gif如下，用代理的方式传递点击OK或者cancel的事件。

二 实现过程

2.1 接口设计

这里仅仅声明了一个初始化方法，一个show方法，以及声明了一个代理，用代理来传值。如果想要自己写一个库的话，API要设计的更完善一些，这里仅仅是为了demo，不搞得那么复杂。

@protocol WCALertviewDelegate<NSObject>
@optional
-(void)didClickButtonAtIndex:(NSUInteger)index;

@end

@interface WCAlertview : UIView
@property (weak,nonatomic) id<WCALertviewDelegate> delegate;
-(instancetype)initWithTitle:(NSString *) title Image:(UIImage *)image CancelButton:(NSString *)cancelButton OkButton:(NSString *)okButton;
- (void)show;
@end

可以把当前的view作为subview添加到keyWindow，并且设计一个backgroundview，让其的背景色为黑色，透明度为0.4，这就形成了模态展示。

同时，要为backgroundview添加tap手势，让其点击的时候，能够让alertview消失。然后，用一个UIView作为实际展示alertview的实体。所以，层次关系如下

WCAlertview包括backgroubdview以及alertview实体，alertview实体包括图片，title，button等。

为了用UIDynamic Animation，要保存一个Animator的属性。

所以，私有属性应该包括这些

@property (strong,nonatomic)UIDynamicAnimator * animator;
@property (strong,nonatomic)UIView * alertview;
@property (strong,nonatomic)UIView * backgroundview;
@property (strong,nonatomic)NSString * title;
@property (strong,nonatomic)NSString * cancelButtonTitle;
@property (strong,nonatomic)NSString * okButtonTitle;
@property (strong,nonatomic)UIImage * image;

backgroundview实现如下

self.backgroundview = [[UIView alloc] initWithFrame:[[UIApplication sharedApplication] keyWindow].frame];
    self.backgroundview.backgroundColor = [UIColor blackColor];
    self.backgroundview.alpha = 0.4;
    [self addSubview:self.backgroundview];

    UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(click:)];
    [self.backgroundview addGestureRecognizer:tap];

tap的响应函数

-(void)click:(UITapGestureRecognizer *)sender{
    CGPoint tapLocation = [sender locationInView:self.backgroundview];
    CGRect alertFrame = self.alertview.frame;
    if (!CGRectContainsPoint(alertFrame, tapLocation)) {
        [self dismiss];
    }
}

这里的dismiss是让整个WCAlertview消失，注意，要判断点击的点是否在alertview实体内，如果不在，才应该dismiss

dismiss采用UIView的动画

-(void)dismiss{
    [self.animator removeAllBehaviors];
    [UIView animateWithDuration:0.7 animations:^{
        self.alpha = 0.0;
        CGAffineTransform rotate = CGAffineTransformMakeRotation(0.9 * M_PI);
        CGAffineTransform scale = CGAffineTransformMakeScale(0.1, 0.1);
        self.alertview.transform = CGAffineTransformConcat(rotate, scale);
    } completion:^(BOOL finished) {
        [self removeFromSuperview];
         self.alertview = nil;
    }];

}

简单的UI控件堆砌

self.alertview = [[UIView alloc] initWithFrame:CGRectMake(0, 0, alertviewWidth, 250)];
    self.alertview.layer.cornerRadius = 17;
    UIView * keywindow = [[UIApplication sharedApplication] keyWindow];
    self.alertview.center = CGPointMake(CGRectGetMidX(keywindow.frame), -CGRectGetMidY(keywindow.frame));
    self.alertview.backgroundColor = [UIColor whiteColor];
    self.alertview.clipsToBounds = YES;

    [self addSubview:self.alertview];

    UILabel * titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(0,0,alertviewWidth,titleHeight)];
    titleLabel.text = self.title;
    titleLabel.textAlignment = NSTextAlignmentCenter;
    [self.alertview addSubview:titleLabel];

    UIImageView * imageview = [[UIImageView alloc] initWithFrame:CGRectMake(0,titleHeight, alertviewWidth,imageviewHeight)];
    imageview.contentMode = UIViewContentModeScaleToFill;
    imageview.image = self.image;
    imageview.layer.borderColor = [UIColor lightGrayColor].CGColor;
    imageview.layer.borderWidth = 0.5;
    [self.alertview addSubview:imageview];

    CGRect cancelButtonFrame = CGRectMake(0, titleHeight + imageviewHeight,alertviewWidth,buttonHeight);
    if (self.okButtonTitle.length != 0 && self.okButtonTitle !=nil) {
        cancelButtonFrame = CGRectMake(alertviewWidth / 2 ,titleHeight + imageviewHeight, alertviewWidth/2,buttonHeight);
        CGRect okButtonFrame = CGRectMake(0,titleHeight + imageviewHeight, alertviewWidth/2,buttonHeight);
        UIButton * okButton = [self createButtonWithFrame:okButtonFrame Title:self.okButtonTitle];
        okButton.tag = 2;
        [self.alertview addSubview:okButton];

    }
    UIButton * cancelButton = [self createButtonWithFrame:cancelButtonFrame Title:self.cancelButtonTitle];
    cancelButton.tag = 1;
    [self.alertview addSubview:cancelButton];

讲解几点

• 给button设计tag是为了区分点击了哪个button
• 由于本demo支持仅有一个cancel button，所以，在初始化的时候要判断几个button来进行frame的调整
• cancelButton和OKbutton有很多一致的地方，所以用一个函数来创建，避免代码重复。

-(UIButton *)createButtonWithFrame:(CGRect)frame Title:(NSString *)title
{
    UIButton * button = [[UIButton alloc] initWithFrame:frame];
    button.titleLabel.textAlignment = NSTextAlignmentCenter;
    [button setTitle:title forState:UIControlStateNormal];
    [button setTitleColor:[UIColor blueColor]forState:UIControlStateNormal];
    button.titleLabel.textColor = [UIColor blueColor];
    button.titleLabel.textAlignment = NSTextAlignmentCenter;
    button.layer.borderWidth = 0.5;
    button.layer.borderColor = [UIColor lightGrayColor].CGColor;
    [button addTarget:self action:@selector(clickButton:) forControlEvents:UIControlEventTouchUpInside];
    [button setShowsTouchWhenHighlighted:YES];
    return button;
}

2.4 API实现

• 用snap的dynamic animation来让整个view出现
• 初始化的函数中，只是需要把值传递给自己的属性

- (void)show {
    UIView * keywindow = [[UIApplication sharedApplication] keyWindow];
    [keywindow addSubview:self];
    self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self];
    UISnapBehavior * sanp = [[UISnapBehavior alloc] initWithItem:self.alertview snapToPoint:self.center];
    sanp.damping = 0.7;
    [self.animator addBehavior:sanp];
}

-(instancetype)initWithTitle:(NSString *) title
                       Image:(UIImage *)image
                CancelButton:(NSString *)cancelButton
                    OkButton:(NSString *)okButton{
    if (self = [super initWithFrame:[[UIApplication sharedApplication] keyWindow].frame]) {
        self.title = title;
        self.image = image;
        self.cancelButtonTitle = cancelButton;
        self.okButtonTitle = okButton;

        [self setUp];
    }
    return self;
}

2.5 用代理传值

-(void)clickButton:(UIButton *)button{
    if ([self.delegate respondsToSelector:@selector(didClickButtonAtIndex:)]) {
        [self.delegate didClickButtonAtIndex:(button.tag -1)];
    }
    [self dismiss];
}

2.6在使用地方

#import "WCAlertview.h"
@interface ViewController ()<WCALertviewDelegate>

@end

@implementation ViewController
- (IBAction)show:(id)sender {
    WCAlertview * alert = [[WCAlertview alloc] initWithTitle:@"Tite"
                                                       Image:[UIImage imageNamed:@"Image1.jpg"]
                                                CancelButton:@"Cancel"
                                                    OkButton:@"OK"];
    alert.delegate = self;
    [alert show];
}
-(void)didClickButtonAtIndex:(NSUInteger)index{
    switch (index) {
        case 0:
            NSLog(@"Click Cancel");
            break;
        case 1:
            NSLog(@"Click OK");

            break;
        default:
            break;
    }
}

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