27个iOS开发中的小技巧
iOS开发中，相信大家都会遇到这样或那样的问题，于是在本篇文章中，小编整理了一些大家可能能用到的小技巧，希望会对iOS开发者们有所帮助。
[以下资料小编收集自互联网、叶孤城___的博客]
1、不想让TableView显示无用的Cell分割线怎么办？
|
1
|
self.tableView.tableFooterView = [[UIView alloc] init];
|
2、自定义了leftBarbuttonItem左滑返回手势失效了怎么办？
|
1
2
3
4
5
6
|
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]
initWithImage:img
style:UIBarButtonItemStylePlain
target:self
action:@selector(onBack:)];
self.navigationController.interactivePopGestureRecognizer.delegate = (id<uigesturerecognizerdelegate>)self;</uigesturerecognizerdelegate>
|
3、在ioS7中，如何检测系统自带ViewController手势返回结束？
|
1
2
3
4
5
6
7
|
-(
void
)navigationController:(UINavigationController*)navigationControllerwillShowViewController:(UIViewController*)viewControlleranimated:(
BOOL
)animated
{
id<UIViewControllerTransitionCoordinator>tc=navigationController.topViewController.transitionCoordinator;
[tcnotifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext>context){
NSLog(@
"7:%i"
,[contextisCancelled]);
}];
}
|
4、ScrollView莫名其妙不能在viewController划到顶怎么办？
|
1
|
self.automaticallyAdjustsScrollViewInsets = NO;
|
5、在不新建一个Cell的情况下，怎么调整separaLine的位置？
|
1
|
_myTableView.separatorInset = UIEdgeInsetsMake(0, 100, 0, 0);
|
6、怎么点击self.view就让键盘收起，需要添加一个tapGestures吗？
|
1
2
3
4
|
- (
void
)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
[self.view endEditing:YES];
}
|
7、怎么像safari一样滑动的时候隐藏navigationbar？
|
1
|
navigationController.hidesBarsOnSwipe = Yes
|
8、导航条返回键带的title太讨厌了，怎么让它消失？
|
1
2
|
[[UIBarButtonItem appearance] setBackButtonTitlePositionAdjustment:UIOffsetMake(0, -60)
forBarMetrics:UIBarMetricsDefault];
|
9、CollectionView 怎么实现tableview那种悬停的header？
|
1
|
CSStickyHeaderFlowLayou
|
10、能不能只用一个pan手势来代替UISwipegesture的各个方向？
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
|
- (
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
;
}
}
|
11、怎么把tableview里cell的小对勾的颜色改成别的颜色？
|
1
|
_mTableView.tintColor = [UIColor redColor];
|
12、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？
|
1
2
3
4
|
- (
void
)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(
BOOL
)animated
{
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
}
|
13、怎么把我的navigationbar弄成透明的而不是带模糊的效果？
|
1
2
3
4
|
[self.navigationBar setBackgroundImage:[UIImage
new
]
forBarMetrics:UIBarMetricsDefault];
self.navigationBar.shadowImage = [UIImage
new
];
self.navigationBar.translucent = YES;
|
14、怎么改变uitextfield placeholder的颜色和位置？
继承uitextfield，重写这个方法：
|
1
2
3
4
|
- (
void
) drawPlaceholderInRect:(CGRect)rect {
[[UIColor blueColor] setFill];
[self.placeholder drawInRect:rect withFont:self.font lineBreakMode:UILineBreakModeTailTruncation alignment:self.textAlignment];
}
|
15、添加需要的不同语言字符串
简体中文Localizable.strings文件：
|
1
2
3
4
|
"REMIND"
=
"提示"
;
"OK"
=
"确定"
;
"CANCEL"
=
"取消"
;
"NetworkConnectError"
=
"网络连接失败"
;
|
英文版Localizable.strings文件：
|
1
2
3
4
|
"REMIND"
=
"Remind"
;
"OK"
=
"OK"
;
"CANCEL"
=
"Cancel"
;
"NetworkConnectError"
=
"Cannot Connect Network"
;
|
注意：不要遗漏结尾的分号“;”
16、使用国际化文件
|
1
2
|
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@
"REMIND"
, nil) message:NSLocalizedString(@
"NetworkConnectError"
, nil) delegate:self cancelButtonTitle:NSLocalizedString(@
"CANCEL"
, nil) otherButtonTitles:NSLocalizedString(@
"OK"
, nil), nil];
[alert show];
|
17、遍历实践Tips
倒序遍历
NSArray和NSOrderedSet都支持使用reverseObjectEnumerator倒序遍历，如：
|
1
2
3
4
|
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：
|
1
2
3
|
[array enumerateObjectsWithOptions:NSEnumerationReverse usingBlock:^(Sark *sark, NSUInteger idx,
BOOL
*stop) {
[sark doSomething];
}];
|
使用block同时遍历字典key，value
block版本的字典遍历可以同时取key和value（forin只能取key再手动取value），如：
|
1
2
3
4
|
NSDictionary *dict = @{@
"a"
: @
"1"
, @
"b"
: @
"2"
};
[dict enumerateKeysAndObjectsUsingBlock:^(id key, id obj,
BOOL
*stop) {
NSLog(@
"key: %@, value: %@"
, key, obj);
}];
|
对于耗时且顺序无关的遍历，使用并发版本：
|
1
2
3
|
[array enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(Sark *sark, NSUInteger idx,
BOOL
*stop) {
[sark doSomethingSlow];
}];
|
18、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？
|
1
2
3
4
5
6
7
8
|
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];
|
19、如何判断邮箱输入的是否正确？
|
1
2
3
4
5
6
7
8
9
|
- (
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];
}
|
20、如何把当前的视图作为照片保存到相册中去？
|
1
2
3
4
5
6
7
8
9
10
11
|
#import <QuartzCore/QuartzCore.h>
UIGraphicsBeginImageContext(currentView.bounds.size);
//currentView 当前的view
[currentView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
|
21、本地通知（类似于push通知）按home键到后台十秒后触发
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
|
UILocalNotification *notification=[[UILocalNotification alloc] init];
if
(notification!=nil) {
NSLog(@
">> support local notification"
);
NSDate *now=[NSDate
new
];
notification.fireDate=[now addTimeInterval:10];
notification.timeZone=[NSTimeZone defaultTimeZone];
notification.alertBody=@
"该去吃晚饭了！"
;
[[UIApplication sharedApplication].scheduleLocalNotification:notification];
}
|
22、捕获iphone通话事件
|
1
2
3
4
5
6
7
8
9
|
CTCallCenter *center = [[CTCallCenter alloc] init];
center.callEventHandler = ^(CTCall *call)
{
NSLog(@
"call:%@"
, call.callState);
}
|
23、计算字符串的字数
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
-(
int
)calculateTextNumber:(NSString *)text
{
float
number = 0.0;
int
index = 0;
for
(index; index < [text length]; index++)
{
NSString *protoText = [text substringToIndex:[text length] - index];
NSString *toChangetext = [text substringToIndex:[text length] -1 -index];
NSString *charater;
if
([toChangetext length]==0)
{
charater = protoText;
}
else
{
NSRange range = [text rangeOfString:toChangetext];
charater = [protoText stringByReplacingCharactersInRange:range withString:@
""
];
}
NSLog(charater);
if
([charater lengthOfBytesUsingEncoding:NSUTF8StringEncoding] == 3)
{
number++;
}
else
{
number = number+0.5;
}
}
return
ceil
(number);
}
|
24、iPad隐藏键盘的同时触发方法
|
1
2
3
4
5
6
7
8
9
|
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(keyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
- (IBAction)keyboardWillHide:(NSNotification *)note
|
25、设置时区
|
1
2
3
4
5
|
NSTimeZone *defaultTimeZone = [NSTimeZone defaultTimeZone];
NSTimeZone *tzGMT = [NSTimeZone timeZoneWithName:@
"GMT"
];
[NSTimeZone setDefaultTimeZone:tzGMT];
|
26、在程序中实现电话的拨打
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
//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
}
|
27、实现自定义的状态栏（遮盖状态栏）
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
|
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];
|