iOS Development Hundred Questions (11)

131, how to limit scrollview in a certain direction is not scrollable?

For example, to restrict non-scrolling in the x direction, you can implement the Uiscrollviewdelegate protocol method:

Func Scrollviewdidscroll (Scrollview:uiscrollview) {

Ifabs (Scrollview.contentoffset.x) > 0 {

Scrollview.contentoffset= cgpointmake (0, Scrollview.contentoffset.y)

}

}

132. How to import the O-C framework into the SWIFT framework target

Take BMOBSDK as an example (the same is true for c/o-c frameworks such as Commoncrypto), and when you add bmobsdk to link Binary with libraries, an error occurs when you use the "IMPORTBMOBSDK" statement: No Such module

If you try to import bmobsdk using bridging headers, you will cause another error.

This is because the SWIFT framework does not support bridging headers files.

To solve this problem, you need to go through the following steps:
1) Create the BMOBSDK directory in the project directory and place the bmobsdk.framework in this directory. Also create a module.map file in this directory with the following contents:

Module BMOBSDK [System] {

Header "/users/kmyhy/documents/swift/code/12th Chapter/knote/bmobsdk/bmobsdk.framework/headers/bmob.h"

Link "bmobsdk"

Export *

}

This will allow us to use the BMOBSDK as Swift module.

2) In Build settings, locate the import Paths (swift_include_paths) and add the BMOBSDK directory. As shown in the following:

3) Import the BMOBSDK framework into the Swift file:

Import BMOBSDK

133. How to use Cocoapods in app extension

Add this sentence to the Podfile:

Link_with ' extension's name '

Add the bridging header file and set the Objective-c Bridgingheader.

134. Error ' XXX.PCH ' has been modified since the precompiled header is builterror in Xcode

Execute depth Clean (shortcut key option+command+shift+k)

135. In Document provider extension, the Documentstorageurl property of Documentpickerviewcontroller is returned as nil.

Confirm that the app groups settings for the container app,document provider extension and file provider extension are correct, and if there are any exclamation points, please fixed.

136. Inserting and deleting cells in CollectionView

Like TableView, we can insert/delete cells with insertitemsatindexpaths ()/deleteitemsatindexpaths (). The difference is that Collecionview no longer supports the beginupdates ()/endupdates () operation. Insert/Delete animations are supported by default, and you can set the Animationsenabled property of UIView If you do not want the default animation effect:

BOOL animationsenabled = [UIView areanimationsenabled];

[UIView Setanimationsenabled:no];

[Mycollectionview reloaditemsatindexpaths:myindexpaths];

[UIView setanimationsenabled:animationsenabled];

137, Uiscrollview in the Uicollectionview will not scroll

Check whether the Uiscrollview is set with the Delegate property, and check whether the Scrollviewdidscroll method is implemented in delegate. If so, delete the method (simply canceling the delegate property is not possible).

Also check the width (or width constraint), height (or height constraint) of the Uicollectionview, and the size of the list content, because scroll bars in that direction do not appear when the contents of the list are smaller than the width (or height) of Uicollectionview.

138, cell use UITableViewCellStyleValue1, why is not displayed correctly?

UITableViewCell has several built-in types, such as Uitableviewcellstyledefault, UITableViewCellStyleValue1, and UITableViewCellStyleValue2.

These cells are pre-configured in the SDK, and they present fixed built-in styles such as font size, color, alignment, and so on. If you want to modify these configurations, it is likely to show abnormal, such as some text can be displayed at a sudden, do not display at once, or suddenly display the inherent font (and color), suddenly (for example, click on the cell) and display the modified font (and color).

In this case, you'd better customize your own cell (subclass).

139, Boundingrectwithsize calculated the size is not correct?

Note the correct options parameters are provided. For Uilabel, you need to use at least the Useslinefragmentorigin and usesfontleading two options:

CGRect Paragraphrect =

[Attributedtextboundingrectwithsize:cgsizemake (300.F, Cgfloat_max)

Options: (nsstringdrawinguseslinefragmentorigin| nsstringdrawingusesfontleading)

Context:nil];

140. Cannot perform bitwise OR (|) operations on multiple enumeration values in Swift

Note that this issue was addressed in IOS 8.3 SDK Beta 1 (12f5027d). For the SDK below this version, we can replace it with the following code:

Let Options =unsafebitcast (NSStringDrawingOptions.UsesLineFragmentOrigin.rawValue |

NSStringDrawingOptions.UsesFontLeading.rawValue,

Nsstringdrawingoptions.self)

Let frame = text.boundingrectwithsize (size, options:options, Attributes:d,context:nil)

iOS Development Hundred Questions (11)