ios开发小技巧

[self.navigationController.view addSubview:bgView];

全屏的视图层


自定义了leftBarbuttonItem左滑返回手势失效了怎么办?

ScrollView莫名其妙不能在viewController划到顶怎么办?

self.automaticallyAdjustsScrollViewInsets = NO;

怎么在不新建一个Cell的情况下调整separaLine的位置?

_myTableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);

怎么像safari一样滑动的时候隐藏navigationbar?

navigationController.hidesBarsOnSwipe = Yes

导航条返回键带的title太讨厌了,怎么让它消失!

​[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)

forBarMetrics:UIBarMetricsDefault];

更改系统默认返回的《按钮的颜色为白色

self.navigationController.navigationBar.tintColor = [UIColor whiteColor];​

// 设置系统默认导航条的颜色

if ([self.navigationController.navigationBarrespondsToSelector:@selector(setBarTintColor:)]) {

[self.navigationController.navigationBarsetBarTintColor:[UIColorblackColor]];

}

else {

[self.navigationController.navigationBarsetTintColor:[UIColorblackColor]];

}

[self.navigationController.navigationBarsetTitleTextAttributes:

@{NSFontAttributeName:[UIFontsystemFontOfSize:19],

NSForegroundColorAttributeName:[UIColorwhiteColor]}]; // 设置系统默认title的颜色

CollectionView 怎么实现tableview那种悬停的header?

CSStickyHeaderFlowLayou

拉伸图片的时候怎么才能让图片不变形?1.UIImage *image = [[UIImage imageNamed:@"xxx"] stretchableImageWithLeftCapWidth:10 topCapHeight:10];​

怎么把tableview里cell的小对勾的颜色改成别的颜色?

_mTableView.tintColor = [UIColor redColor];

本来我的statusbar是lightcontent的,结果用UIImagePickerController会导致我的statusbar的样式变成黑色,怎么办?​

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated

{

[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

​}

怎么把我的navigationbar弄成透明的而不是带模糊的效果?

[self.navigationBar setBackgroundImage:[UIImage new]

forBarMetrics:UIBarMetricsDefault];

self.navigationBar.shadowImage = [UIImage new];

self.navigationBar.translucent = YES;

怎么改变uitextfield placeholder的颜色和位置?

继承uitextfield,重写这个方法

- (void) drawPlaceholderInRect:(CGRect)rect {

[[UIColor blueColor] setFill];

[self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];

}

实现自定义的状态栏(遮盖状态栏)

CGRect frame = {{0, 0}, {320, 20}};

UIWindow* wd = [[UIWindow alloc] initWithFrame:frame];

[wd setBackgroundColor:[UIColor clearColor]];

[wd setWindowLevel:UIWindowLevelStatusBar];

frame = CGRectMake(100, 0, 30, 20);

UIImageView* img = [[UIImageView alloc] initWithFrame:frame];

[img setContentMode:UIViewContentModeCenter];

[img setImage:[UIImage imageNamed:@"00_0103.png"]];

[wd addSubview:img];

[wd makeKeyAndVisible];

[UIView beginAnimations:nil context:nil];

[UIView setAnimationDuration:2];

frame.origin.x += 150;

[img setFrame:frame];

[UIView commitAnimations];

​在程序中实现电话的拨打

//添加电话图标按钮

UIButton *btnPhone = [[UIButton buttonWithType:UIButtonTypeCustom] retain];

btnPhone.frame = CGRectMake(280,10,30,30);

UIImage *image = [UIImage imageNamed:@"phone.png"];

[btnPhone setBackgroundImage:image forState:UIControlStateNormal];

//点击拨号按钮直接拨号

[btnPhone addTarget:self action:@selector(callAction:event:)forControlEvents:UIControlEventTouchUpInside];

[cell.contentView addSubview:btnPhone];  //cell是一个UITableViewCell

//定义点击拨号按钮时的操作

- (void)callAction:(id)sender event:(id)event{

NSSet *touches = [event allTouches];

UITouch *touch = [touches anyObject];

CGPoint currentTouchPosition = [touch locationInView:self.listTable];

NSIndexPath *indexPath = [self.listTable indexPathForRowAtPoint: currentTouchPosition];

if (indexPath == nil) {

return;

}

NSInteger section = [indexPath section];

NSUInteger row = [indexPath row];

NSDictionary *rowData = [datas objectAtIndex:row];

NSString *num = [[NSString alloc] initWithFormat:@"tel://%@

",number]; //number为号码字符串

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:num]]; //拨号

}

设置时区​

NSTimeZone *defaultTimeZone = [NSTimeZone defaultTimeZone];

NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@"GMT"];

[NSTimeZone setDefaultTimeZone:tzGMT];

捕获iphone通话事件​

CTCallCenter *center = [[CTCallCenter alloc] init];

center.callEventHandler = ^(CTCall *call)

{

NSLog(@"call:%@", call.callState);

}

如何判断邮箱输入的是否正确?​

- (BOOL) validateEmail: (NSString *) candidate {

NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}";

NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];

return [emailTest evaluateWithObject:candidate];

}

如果在程序中想对某张图片进行处理的话(如得到某张图片的一部分)怎么做?​

UIImage *image = [UIImage imageNamed:filename];

CGImageRef imageRef = image.CGImage;

CGRect rect = CGRectMake(origin.x, origin.y ,size.width, size.height);

CGImageRef imageRefRect = CGImageCreateWithImageInRect(imageRef, rect);

UIImage *imageRect = [[UIImage alloc] initWithCGImage:imageRefRect];

倒序遍历

NSArray和NSOrderedSet都支持使用reverseObjectEnumerator倒序遍历,如:NSArray *strings = @[@"1", @"2", @"3"];

for (NSString *string in [strings reverseObjectEnumerator]) {

NSLog(@"%@", string);

}

这个方法只在循环第一次被调用,所以不必担心循环每次计算的问题。

同时,使用enumerateObjectsWithOptions:NSEnumerationReverse也可以实现倒序遍历:[array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(Sark *sark, NSUInteger idx, BOOL *stop) {

[sark doSomething];

}];

只用一个pan手势来代替UISwipegesture的各个方向​

​- (void)pan:(UIPanGestureRecognizer *)sender

{

typedef NS_ENUM(NSUInteger, UIPanGestureRecognizerDirection) {

UIPanGestureRecognizerDirectionUndefined,

UIPanGestureRecognizerDirectionUp,

UIPanGestureRecognizerDirectionDown,

UIPanGestureRecognizerDirectionLeft,

UIPanGestureRecognizerDirectionRight

};

static UIPanGestureRecognizerDirection direction = UIPanGestureRecognizerDirectionUndefined;

switch (sender.state) {

case UIGestureRecognizerStateBegan: {

if (direction == UIPanGestureRecognizerDirectionUndefined) {

CGPoint velocity = [sender velocityInView:recognizer.view];

BOOL isVerticalGesture = fabs(velocity.y) > fabs(velocity.x);

if (isVerticalGesture) {

if (velocity.y > 0) {

direction = UIPanGestureRecognizerDirectionDown;

} else {

direction = UIPanGestureRecognizerDirectionUp;

}

}

else {

if (velocity.x > 0) {

direction = UIPanGestureRecognizerDirectionRight;

} else {

direction = UIPanGestureRecognizerDirectionLeft;

}

}

}

break;

}

case UIGestureRecognizerStateChanged: {

switch (direction) {

case UIPanGestureRecognizerDirectionUp: {

[self handleUpwardsGesture:sender];

break;

}

case UIPanGestureRecognizerDirectionDown: {

[self handleDownwardsGesture:sender];

break;

}

case UIPanGestureRecognizerDirectionLeft: {

[self handleLeftGesture:sender];

break;

}

case UIPanGestureRecognizerDirectionRight: {

[self handleRightGesture:sender];

break;

}

default: {

break;

}

}

break;

}

case UIGestureRecognizerStateEnded: {

direction = UIPanGestureRecognizerDirectionUndefined;

break;

}

default:

break;

}

}

在ioS7中,如何检测系统自带ViewController手势返回结束?​

​-(void)navigationController:(UINavigationController*)navigationControllerwillShowViewController:(UIViewController*)viewControlleranimated:(BOOL)animated

{

idtc=navigationController.topViewController.transitionCoordinator;

[tcnotifyWhenInteractionEndsUsingBlock:^(idcontext){

NSLog(@"7:%i",[contextisCancelled]);

}];

}

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