iOS开发基础知识碎片

1:contentSize、contentInset和contentOffset区别

contentSize 是scrollview中的一个属性，它代表scrollview中的可显示区域，假如有一个scrollview，它的frame为(0,0,320,480),而它的contentSize为(320,960).也就是说，这个scrollview整个内容的大小为(320,960),要通过上下滑动scrollview来查看(320,480)后的内容。

contentOffset 是scrollview当前显示区域顶点相对于frame顶点的偏移量，比如上个例子你拉到最下面，contentoffset就是(0 ,-480)，也就是y偏移了480

contentInset 是scrollview中contentView.frame.origin与scrollview.frame.origin的关系，比如contentView的frame为(0,30,320,480),那么contentInset则为(0, 30),它也可以设置上下左右

2:IOS虚拟器安装其它Simulator

下载后的dmg安装.这里主要以iOS7.0模拟器的离线安装为例进行说明，其他版本以此类推：

下载ios_7_0_simulator.dmg后打开dmg文件，可以看到安装包iPhoneSimulatorSDK7_0.pkg，使用安装器安装此安装包，默认会安装在所选分区的/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator7.0.sdk目录下，完全退出Xcode后将刚才安装的iPhoneSimulator7.0.sdk整个目录复制或移动到/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs目录下即可，(Xcode.app右键可以"显示包内容“)重新启动Xcode一般就可以使用相应版本的模拟器进行开发和调试了。

离线安装还有一个简单的办法就是将以前安装过的旧版本的Xcode如Xcode5.0.2下面已经安装好了的iOS模拟器直接复制过来使用，目录位置都一样，都是在Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs里面。这样就不用再下载离线安装包了。

3:输入框中的inputaccessoryview和inputview

UITextFields和UITextView有一个inputAccessoryView的属性，当你想在键盘上展示一个自定义的view时，你就可以设置该属性。你设置的view就会自动和键盘keyboard一起显示了。需要注意的是，你所自定义的view既不应该处在其他的视图层里，也不应该成为其他视图的子视图。其实也就是说，你所自定义的view只需要赋给属性inputAccessoryView就可以了，不要再做其他多余的操作。

inputview则是键盘视图，当其为nil时则弹出的是系统默认的键盘；

实例一(给键盘上方设置一个工具条的方式)：

- (void)createKeyboardTool
{
    keyboardTool = [[UIToolbar alloc] initWithFrame: CGRectMake(kZero, kZero, kScreenW, 44.0f)];
    NSMutableArray *myToolBarItems = [NSMutableArray array];

　　//创建键盘工具条上面的按钮,并设置点击事件
    UIBarButtonItem *cancelBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemReply target:self action:@selector(cancelAction)];
    UIBarButtonItem *space = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:self action:@selector(saveAction)];
    UIBarButtonItem *saveBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(saveAction)];

    [myToolBarItems addObject:cancelBtn];
    [myToolBarItems addObject:space];
    [myToolBarItems addObject:saveBtn];
    keyboardTool.items = myToolBarItems;
}

//inputAccessoryView:设置键盘顶部显示的工具条;inputView:自定义键盘
    commentTextView = [[UITextView alloc]initWithFrame:CGRectMake(kZero, kZero, kScreenW, 200)];
    [commentTextView becomeFirstResponder];
    commentTextView.inputAccessoryView = keyboardTool;

实例二(修改键盘视图，进行切换自定义视图跟系统自带视图)：

/**
 *  切换键盘
 */
- (void)switchKeyboard
{
    // self.textView.inputView == nil : 使用的是系统自带的键盘
    if (self.textView.inputView == nil) {
        // 切换为自定义的表情键盘 emtionKeyboard为一个视图
        self.textView.inputView = self.emotionKeyboard;
        // 显示键盘按钮
        self.toolbar.showKeyboardButton = YES;
    } else {
        // 切换为系统自带的键盘
        self.textView.inputView = nil;
        // 显示表情按钮
        self.toolbar.showKeyboardButton = NO;
    }
    // 开始切换键盘 这个是为固定用的
    self.switchingKeybaord = YES;
    // 退出键盘
    [self.textView endEditing:YES];
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        // 弹出键盘,让其慢点实现
        [self.textView becomeFirstResponder];
        // 结束切换键盘
        self.switchingKeybaord = NO;
    });
}

/**
 * 键盘的frame发生改变时调用（显示、隐藏等）
 */
- (void)keyboardWillChangeFrame:(NSNotification *)notification
{
    // 如果正在切换键盘，就不要执行后面的代码
    if (self.switchingKeybaord) return;

    NSDictionary *userInfo = notification.userInfo;
    // 动画的持续时间
    double duration = [userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
    // 键盘的frame
    CGRect keyboardF = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];

    // 执行动画
    [UIView animateWithDuration:duration animations:^{
        // 工具条的Y值 == 键盘的Y值 - 工具条的高度
        if (keyboardF.origin.y > self.view.height) { // 键盘的Y值已经远远超过了控制器view的高度
            self.toolbar.y = self.view.height - self.toolbar.height;
        } else {
            self.toolbar.y = keyboardF.origin.y - self.toolbar.height;
        }
    }];
}

4:修改UISearchBar中关于cannel取消的文字

-(UISearchBar *)mySearchBar
{
    if (_mySearchBar==nil) {
        _mySearchBar=[[UISearchBar alloc]init];
        _mySearchBar.showsCancelButton=YES;
        _mySearchBar.delegate=self;
        [_mySearchBar sizeToFit];
        [_mySearchBar setPlaceholder:@"请输入"];
        [_mySearchBar setY:20];

        //处理cannel的文字显示
        for (id item in [_mySearchBar subviews]) {
            for(id cc in [item subviews])
            {
                if ([cc isKindOfClass:[UIButton class]]) {
                    UIButton *btn=(UIButton *)cc;
                    [btn setTitle:@"取消" forState:UIControlStateNormal];
                }
            }
        }
    }
    return _mySearchBar;
}

如果是获得瞧点才显示出取消可以在这个委托里面进行设置:

/**
 *  @author wujunyang, 15-06-24 11:06:44
 *
 *  @brief  修改cancel的显示文字 必先把showscancelButton设置为yes
 *  @param searchBar <#searchBar description#>
 */
- (void)searchBarTextDidBeginEditing:(UISearchBar *)searchBar
{
    searchBar.showsCancelButton=YES;
    for (id item in [searchBar subviews]) {
        for(id cc in [item subviews])
        {
        if ([cc isKindOfClass:[UIButton class]]) {
            UIButton *btn=(UIButton *)cc;
            [btn setTitle:@"取消" forState:UIControlStateNormal];
        }
        }
    }
}

5:关于navigationController中增加控件时push跳转及跳回

在子页navigationController增加控件,回跳时它是没办法自个销除，所以要手动增加一个销除nav所增加的控件，否则子页的那个控件会被重叠显示在父页的nav上；如下一个实例：

在viewDidLoad里
//加载控件
    [self.navigationController.view addSubview:self.mySearchBar];

(void)viewWillDisappear:(BOOL)animated {
    //这句也可以写在回跳前
    [self.mySearchBar removeFromSuperview];
    [super viewWillDisappear:animated];
}

6:整个视图点击都对键盘进行收缩

- (void)viewDidLoad {
    [super viewDidLoad];
    UITapGestureRecognizer *tapGr=[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(viewTapped:)];
    //如果没有这句在view中的Button等可能无法触发ToucheUpInside事件
    tapGr.cancelsTouchesInView=NO;
    [self.view addGestureRecognizer:tapGr];
}
- (IBAction)BtnAction:(id)sender {
    NSLog(@"%@",self.myTextField.text);
}
-(void)viewTapped:(UITapGestureRecognizer *)tapGr
{
    [self.myTextField resignFirstResponder];
}
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}
@end

7:针对第三方插件为mrc，而工程为arc的调用

对第三方插件的.m文件进行设置，工程targets-build phases－compile sources 设置-fno-objc-arc

有些是双星如 PLTexture **previewTextures;
在arc下面则要修改成：PLTexture * __unsafe_unretained *previewTextures;

8:通知的方式实现键盘的收缩布局问题

/**
 *  添加工具条
 */
- (void)setupToolbar
{
    // 1.添加工具条
    IWComposeToolbar *toolbar = [[IWComposeToolbar alloc] init];
    toolbar.delegate = self;
    CGFloat toolbarH = 35;
    CGFloat toolbarW = self.view.width;
    CGFloat toolbarY = self.view.height - toolbarH;
    toolbar.frame = CGRectMake(0, toolbarY, toolbarW, toolbarH);
    [self.view addSubview:toolbar];
    self.toolbar = toolbar;

    // 2.监听键盘的弹出和隐藏
    // 键盘的frame(位置)即将改变, 就会发出UIKeyboardWillChangeFrameNotification
    // 键盘即将弹出, 就会发出UIKeyboardWillShowNotification
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];
    // 键盘即将隐藏, 就会发出UIKeyboardWillHideNotification
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];
}

#pragma mark - 键盘处理
/**
 *  键盘即将隐藏
 */
- (void)keyboardWillHide:(NSNotification *)note
{
    // 1.键盘弹出需要的时间
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    // 2.动画
    [UIView animateWithDuration:duration animations:^{
        self.toolbar.transform = CGAffineTransformIdentity;
    }];
}

/**
 *  键盘即将弹出
 */
- (void)keyboardWillShow:(NSNotification *)note
{
    // 1.键盘弹出需要的时间
    CGFloat duration = [note.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];

    // 2.动画
    [UIView animateWithDuration:duration animations:^{
        // 取出键盘高度
        CGRect keyboardF = [note.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
        CGFloat keyboardH = keyboardF.size.height;
        self.toolbar.transform = CGAffineTransformMakeTranslation(0, - keyboardH);
    }];
}

//通知要销掉
- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

注意：[self.textView resignFirstResponder];放弃瞧点
还有可以监听输入内容的变化：    // 2.监听textView文字的改变
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChange) name:UITextViewTextDidChangeNotification object:textView];

9:封装一个uivew带有按键工具栏的实例

.h文件内容：

#import <UIKit/UIKit.h>

@class IWComposeToolbar;

typedef enum {
    IWComposeToolbarButtonTypeCamera,
    IWComposeToolbarButtonTypePicture,
    IWComposeToolbarButtonTypeMention,
    IWComposeToolbarButtonTypeTrend,
    IWComposeToolbarButtonTypeEmotion
} IWComposeToolbarButtonType;

@protocol IWComposeToolbarDelegate <NSObject>
@optional
- (void)composeToolbar:(IWComposeToolbar *)toolbar didClickButton:(IWComposeToolbarButtonType)butonType;
@end

@interface IWComposeToolbar : UIView
@property (weak, nonatomic) id<IWComposeToolbarDelegate> delegate;
@end

.m文件内容：

#import "IWComposeToolbar.h"

@implementation IWComposeToolbar

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // 1.设置背景
        self.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageWithName:@"compose_toolbar_background"]];

        // 2.添加按钮
        [self addButtonWithIcon:@"compose_camerabutton_background" highIcon:@"compose_camerabutton_background_highlighted" tag:IWComposeToolbarButtonTypeCamera];
        [self addButtonWithIcon:@"compose_toolbar_picture" highIcon:@"compose_toolbar_picture_highlighted" tag:IWComposeToolbarButtonTypePicture];
        [self addButtonWithIcon:@"compose_mentionbutton_background" highIcon:@"compose_mentionbutton_background_highlighted" tag:IWComposeToolbarButtonTypeMention];
        [self addButtonWithIcon:@"compose_trendbutton_background" highIcon:@"compose_trendbutton_background_highlighted" tag:IWComposeToolbarButtonTypeTrend];
        [self addButtonWithIcon:@"compose_emoticonbutton_background" highIcon:@"compose_emoticonbutton_background_highlighted" tag:IWComposeToolbarButtonTypeEmotion];
    }
    return self;
}

- (void)addButtonWithIcon:(NSString *)icon highIcon:(NSString *)highIcon tag:(IWComposeToolbarButtonType)tag
{
    UIButton *button = [[UIButton alloc] init];
    button.tag = tag;
    [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];
    [button setImage:[UIImage imageWithName:icon] forState:UIControlStateNormal];
    [button setImage:[UIImage imageWithName:highIcon] forState:UIControlStateHighlighted];
    [self addSubview:button];
}

/**
 *  监听按钮点击
 */
- (void)buttonClick:(UIButton *)button
{
    if ([self.delegate respondsToSelector:@selector(composeToolbar:didClickButton:)]) {
        [self.delegate composeToolbar:self didClickButton:button.tag];
    }
}

- (void)layoutSubviews
{
    [super layoutSubviews];

    int count = self.subviews.count;
    CGFloat buttonW = self.width / count;
    CGFloat buttonH = self.height;
    for (int i = 0; i<count; i++) {
        UIButton *button = self.subviews[i];
        CGFloat buttonX = buttonW * i;
        button.frame = CGRectMake(buttonX, 0, buttonW, buttonH);
    }
}

@end